refactor(rename): frontend TSX + client TS files, fetch URLs, nav hrefs

t-paliad-025 Phase 3 — frontend rename pass:

File renames (git mv, preserving history):
  frontend/src/
    akten.tsx               → projects.tsx
    akten-neu.tsx           → projects-new.tsx
    akten-detail.tsx        → projects-detail.tsx
    fristen.tsx             → deadlines.tsx
    fristen-neu.tsx         → deadlines-new.tsx
    fristen-detail.tsx      → deadlines-detail.tsx
    fristen-kalender.tsx    → deadlines-calendar.tsx
    termine.tsx             → appointments.tsx
    termine-neu.tsx         → appointments-new.tsx
    termine-detail.tsx      → appointments-detail.tsx
    termine-kalender.tsx    → appointments-calendar.tsx
    einstellungen.tsx       → settings.tsx
    checklisten*.tsx        → checklists*.tsx
    gerichte.tsx            → courts.tsx
    glossar.tsx             → glossary.tsx

  frontend/src/client/ — same renames, plus notizen.ts → notes.ts.

Render exports renamed (renderAkten → renderProjects, renderFristen →
renderDeadlines, …). build.ts rewired to new names.

Client-side changes:
* fetch() API paths: /api/projekte → /api/projects, /api/fristen →
  /api/deadlines, /api/termine → /api/appointments, /api/notizen →
  /api/notes, /api/gerichte → /api/courts, /api/glossar → /api/glossary,
  /api/dezernate → /api/departments, /api/parteien → /api/parties,
  /api/checklisten → /api/checklists. Legacy /api/akten aliases removed.
* Navigation href/template strings: /akten → /projects, /fristen →
  /deadlines, /termine → /appointments, /einstellungen → /settings,
  /notizen → /notes, /checklisten → /checklists, /gerichte → /courts,
  /glossar → /glossary. Nested paths /neu → /new, /verlauf → /events,
  /kinder → /children, /kalender → /calendar, /dokumente → /documents.
* Interface names in client TS: Frist → Deadline, Termin → Appointment,
  Notiz → Note, Partei → Party, Akte → Project, ProjektMini → ProjectMini,
  Dezernat → Department, DezernatMitglied → DepartmentMember.
* JSON wire-format keys follow backend: projekt_id → project_id, akte_id
  → project_id, frist_id → deadline_id, termin_id → appointment_id,
  akten_event_id → project_event_id, dezernat_id → department_id,
  termin_type → appointment_type.

Go handlers (projects_pages.go, deadlines_pages.go, appointments_pages.go,
checklists.go, courts.go, glossary.go) serve the correctly-named HTML
files from dist/.

Kept German (user-facing i18n + product names):
* i18n keys/strings (src/client/i18n.ts) — DE labels and their keys
* Product names: fristenrechner, kostenrechner, gebuehrentabellen

Build verified: go build / vet / test clean; bun run build clean;
dist/ contains all 26 English-named HTML pages.

frontend/src/client/deadlines.ts

@@ -0,0 +1,265 @@
+import { initI18n, onLangChange, t, getLang } from "./i18n";
+import { initSidebar } from "./sidebar";
+
+interface Deadline {
+  id: string;
+  project_id: string;
+  title: string;
+  due_date: string;
+  status: string;
+  source: string;
+  rule_id?: string;
+  project_reference: string;
+  project_title: string;
+  projekt_office: string;
+  rule_code?: string;
+}
+
+interface Project {
+  id: string;
+  aktenzeichen: string;
+  title: string;
+}
+
+interface Summary {
+  overdue: number;
+  this_week: number;
+  upcoming: number;
+  completed: number;
+  total: number;
+}
+
+let allDeadlines: Deadline[] = [];
+let allProjects: Project[] = [];
+let statusFilter = "pending";
+let akteFilter = "";
+let loadedOK = false;
+
+function urlParams(): URLSearchParams {
+  return new URLSearchParams(window.location.search);
+}
+
+async function loadAkten() {
+  try {
+    const resp = await fetch("/api/projects");
+    if (resp.ok) allProjects = await resp.json();
+  } catch {
+    /* non-fatal */
+  }
+}
+
+async function loadSummary() {
+  try {
+    const url = akteFilter
+      ? `/api/deadlines/summary?project_id=${encodeURIComponent(akteFilter)}`
+      : `/api/deadlines/summary`;
+    const resp = await fetch(url);
+    if (!resp.ok) return;
+    const sum: Summary = await resp.json();
+    setCount("sum-overdue", sum.overdue);
+    setCount("sum-week", sum.this_week);
+    setCount("sum-upcoming", sum.upcoming);
+    setCount("sum-completed", sum.completed);
+  } catch {
+    /* non-fatal */
+  }
+}
+
+function setCount(id: string, n: number) {
+  const el = document.getElementById(id);
+  if (el) el.textContent = String(n);
+}
+
+async function loadFristen() {
+  const unavailable = document.getElementById("fristen-unavailable")!;
+  const tableWrap = document.querySelector<HTMLElement>(".akten-table-wrap")!;
+  try {
+    const params = new URLSearchParams();
+    if (statusFilter) params.set("status", statusFilter);
+    if (akteFilter) params.set("project_id", akteFilter);
+    const resp = await fetch(`/api/deadlines?${params.toString()}`);
+    if (resp.status === 503) {
+      unavailable.style.display = "block";
+      tableWrap.style.display = "none";
+      document.getElementById("fristen-empty")!.style.display = "none";
+      return;
+    }
+    if (!resp.ok) {
+      unavailable.style.display = "block";
+      tableWrap.style.display = "none";
+      return;
+    }
+    allFristen = await resp.json();
+    loadedOK = true;
+    render();
+  } catch {
+    unavailable.style.display = "block";
+    tableWrap.style.display = "none";
+  }
+}
+
+function urgencyClass(due: string, status: string): string {
+  if (status === "completed") return "frist-urgency-done";
+  const today = new Date();
+  today.setHours(0, 0, 0, 0);
+  const d = new Date(due + "T00:00:00");
+  const diffDays = Math.floor((d.getTime() - today.getTime()) / 86400000);
+  if (diffDays < 0) return "frist-urgency-overdue";
+  if (diffDays <= 7) return "frist-urgency-soon";
+  return "frist-urgency-later";
+}
+
+function fmtDate(iso: string): string {
+  try {
+    const d = new Date(iso + "T00:00:00");
+    return d.toLocaleDateString(getLang() === "de" ? "de-DE" : "en-GB", {
+      year: "numeric",
+      month: "2-digit",
+      day: "2-digit",
+    });
+  } catch {
+    return iso;
+  }
+}
+
+function esc(s: string): string {
+  const d = document.createElement("div");
+  d.textContent = s;
+  return d.innerHTML;
+}
+
+function render() {
+  if (!loadedOK) return;
+  const tbody = document.getElementById("fristen-body")!;
+  const empty = document.getElementById("fristen-empty")!;
+  const emptyFiltered = document.getElementById("fristen-empty-filtered")!;
+  const tableWrap = document.querySelector<HTMLElement>(".akten-table-wrap")!;
+
+  if (allFristen.length === 0) {
+    tbody.innerHTML = "";
+    tableWrap.style.display = "none";
+    if (statusFilter === "all" && !akteFilter) {
+      empty.style.display = "block";
+      emptyFiltered.style.display = "none";
+    } else {
+      empty.style.display = "none";
+      emptyFiltered.style.display = "block";
+    }
+    return;
+  }
+
+  tableWrap.style.display = "";
+  empty.style.display = "none";
+  emptyFiltered.style.display = "none";
+
+  tbody.innerHTML = allFristen
+    .map((f) => {
+      const urgency = urgencyClass(f.due_date, f.status);
+      const statusLabel = t(`fristen.status.${f.status}`) || f.status;
+      const ruleLabel = f.rule_code ? esc(f.rule_code) : "&mdash;";
+      const checked = f.status === "completed" ? "checked" : "";
+      const disabled = f.status === "completed" ? "disabled" : "";
+      const titleClass = f.status === "completed" ? "frist-title-done" : "";
+      return `<tr class="frist-row" data-id="${esc(f.id)}">
+        <td class="frist-col-check">
+          <input type="checkbox" class="frist-complete-cb" ${checked} ${disabled}
+                 aria-label="${esc(t("fristen.complete.action"))}" />
+        </td>
+        <td class="frist-col-due ${urgency}"><span class="frist-due-dot"></span>${fmtDate(f.due_date)}</td>
+        <td class="frist-col-title ${titleClass}">${esc(f.title)}</td>
+        <td class="frist-col-project">
+          <a class="akten-ref-link" href="/projects/${esc(f.project_id)}">${esc(f.project_reference)}</a>
+          <span class="frist-project-title">${esc(f.project_title)}</span>
+        </td>
+        <td class="frist-col-rule">${ruleLabel}</td>
+        <td><span class="akten-status-chip akten-status-${esc(f.status)}">${esc(statusLabel)}</span></td>
+      </tr>`;
+    })
+    .join("");
+
+  tbody.querySelectorAll<HTMLTableRowElement>(".frist-row").forEach((row) => {
+    const id = row.dataset.id!;
+    row.addEventListener("click", (e) => {
+      // Don't navigate if clicking the checkbox or a link
+      const target = e.target as HTMLElement;
+      if (target.closest(".frist-complete-cb") || target.closest("a")) return;
+      window.location.href = `/deadlines/${id}`;
+    });
+    const cb = row.querySelector<HTMLInputElement>(".frist-complete-cb");
+    if (cb) {
+      cb.addEventListener("change", async () => {
+        if (!cb.checked) return;
+        cb.disabled = true;
+        try {
+          const resp = await fetch(`/api/deadlines/${id}/complete`, { method: "PATCH" });
+          if (resp.ok) {
+            await Promise.all([loadFristen(), loadSummary()]);
+          } else {
+            cb.checked = false;
+            cb.disabled = false;
+          }
+        } catch {
+          cb.checked = false;
+          cb.disabled = false;
+        }
+      });
+    }
+  });
+}
+
+function initFilters() {
+  const status = document.getElementById("frist-filter-status") as HTMLSelectElement;
+  const project = document.getElementById("frist-filter-project") as HTMLSelectElement;
+
+  // Pre-fill from URL
+  const params = urlParams();
+  if (params.has("status")) statusFilter = params.get("status")!;
+  if (params.has("project_id")) akteFilter = params.get("project_id")!;
+  status.value = statusFilter;
+
+  status.addEventListener("change", async () => {
+    statusFilter = status.value;
+    await Promise.all([loadFristen(), loadSummary()]);
+  });
+  project.addEventListener("change", async () => {
+    akteFilter = project.value;
+    await Promise.all([loadFristen(), loadSummary()]);
+  });
+}
+
+function populateAkteFilter() {
+  const sel = document.getElementById("frist-filter-project") as HTMLSelectElement;
+  // Keep the first "all" option, then append sorted Akten.
+  const options: string[] = [
+    `<option value="" data-i18n="fristen.filter.project.all">${esc(t("fristen.filter.project.all"))}</option>`,
+  ];
+  for (const a of allProjects) {
+    options.push(
+      `<option value="${esc(a.id)}">${esc(a.aktenzeichen)} \u2014 ${esc(a.title)}</option>`,
+    );
+  }
+  sel.innerHTML = options.join("");
+  if (akteFilter) sel.value = akteFilter;
+}
+
+function initSummaryCards() {
+  document.querySelectorAll<HTMLButtonElement>(".frist-summary-card").forEach((card) => {
+    card.addEventListener("click", async () => {
+      const newStatus = card.dataset.status!;
+      statusFilter = newStatus;
+      (document.getElementById("frist-filter-status") as HTMLSelectElement).value = newStatus;
+      await Promise.all([loadFristen(), loadSummary()]);
+    });
+  });
+}
+
+document.addEventListener("DOMContentLoaded", async () => {
+  initI18n();
+  initSidebar();
+  initFilters();
+  initSummaryCards();
+  onLangChange(render);
+  await loadAkten();
+  populateAkteFilter();
+  await Promise.all([loadFristen(), loadSummary()]);
+});