mAi: #89 - deadline rule field binary Auto/Custom + canonical rule-label display

t-paliad-258. m's verdict on t-paliad-251's rule UI: "too many options"
(4 'Oral hearings' across courts, etc.). Replace the full deadline_rules
catalog dropdown + sort selector with a binary model and unify the rule
display contract across every surface that prints a rule label.

Binary Rule field on the deadline form
- Auto (default): rule_id is derived from the chosen Type. The resolved
  rule renders read-only as 'Auto | <Name · Citation>' next to the
  field. No catalog picker, no sort options.
- Custom: free-text input. Stored as deadlines.custom_rule_text (new
  nullable column, migration 122). Mutually exclusive with rule_id at
  the persistence boundary.
- Toggle link flips between modes. Re-toggling to Auto re-resolves from
  the current Type — no stale state.

Schema + service (additive)
- migration 122 adds paliad.deadlines.custom_rule_text (nullable).
  Existing rows: empty custom_rule_text + non-null rule_id = Auto-
  equivalent. Both NULL = "keine Regel" (consistent with today).
- models.Deadline.CustomRuleText + service SELECTs include the column.
- CreateDeadlineInput accepts custom_rule_text; the service drops it
  when rule_id is set (catalog wins; simple invariant at the boundary).
- UpdateDeadlineInput grows a {RuleSet, RuleID, CustomRuleText} triple.
  RuleSet=true is the discriminator so absent fields don't overwrite
  the row (PATCH semantics). RuleID and CustomRuleText are mutually
  exclusive in one request; service rejects "both set".
- EventListItem (the /api/events union) carries CustomRuleText so list
  surfaces can render it.

Frontend: deadlines-new
- Drop the rule <select>, the by_proceeding/by_court/alpha sort
  dropdown, the override-warning slot, and the collapsed-by-Regel Typ
  view. Strip the (Rule→Type) auto-fill machinery — direction is now
  one-way (Type → Auto-resolved Rule).
- Keep Type→Rule resolution: resolveAutoRuleForType picks the canonical
  rule by project's proceeding, then jurisdiction match, then first
  candidate. Same logic, just re-aimed at the read-only display.
- Standardtitel preserves the chain (event type → Auto rule label →
  Custom text → proceeding → fallback) so the recipe still produces a
  sensible title even when Custom is used.

Frontend: deadlines-detail
- Read-only display: catalog rule → Name · Citation, else
  custom_rule_text + Custom badge, else legacy rule_code, else "—".
- Edit mode: mirror the create form with the Auto/Custom toggle.
  enterEdit initialises the mode from the persisted deadline; Save
  PATCHes with rule_set:true + the chosen rule pointer.

Rule-label addendum (m's 14:31 follow-up)
- Canonical contract everywhere: Name primary, Citation muted secondary
  ("Notice of Appeal · UPC.RoP.220.1"). Custom rules render the text
  with a "Custom" pill.
- New frontend/src/client/rule-label.ts exports formatRuleLabel /
  formatRuleLabelHTML / formatCustomRuleLabelHTML — one helper per
  shape (plain text vs muted-citation HTML).
- Wired into: deadlines-new Auto display, deadlines-detail read +
  Standardtitel, events.ts ruleDisplay (REGEL column on /events),
  projects-detail.ts Fristen table, views/shape-list.ts generic
  rule column.
- Verfahrensablauf (views/verfahrensablauf-core.ts) already renders
  name + citation chip separately and matches the canonical pattern;
  no change needed. Schriftsätze table is column-shaped (name + code
  in distinct columns) and out of scope per the addendum.

CSS
- New .rule-mode-auto / .rule-mode-custom / .rule-label-* family.
- Drop the dead .rule-sort-select rule and the .event-type-collapsed*
  family (retired with the catalog dropdown).

i18n
- DE+EN. Remove 10 stale keys (rule.none, autofill, autofill_inline,
  mismatch, override, override_warn, sort.*). Add 6 (auto_no_match,
  auto_pick_type, custom_badge, custom_placeholder,
  mode.toggle_to_auto, mode.toggle_to_custom).

Build hygiene
- go build + go test ./internal/... clean.
- frontend bun build clean (2803 keys, scan clean).

Out of scope (per issue)
- Promoting Custom entries back to the catalog ("save as new rule").
- Filtering/searching custom_rule_text in deadline lists.
- Touching the event-type browse modal (Part 1 of #82 — that stays).

Files
- internal/db/migrations/122_deadlines_custom_rule_text.{up,down}.sql
- internal/models/models.go
- internal/services/deadline_service.go (Create+Update+SELECT)
- internal/services/event_service.go (union projection)
- frontend/src/client/rule-label.ts (new helper)
- frontend/src/client/deadlines-new.ts (rewrite)
- frontend/src/client/deadlines-detail.ts (Auto/Custom editor + display)
- frontend/src/client/events.ts (REGEL column)
- frontend/src/client/projects-detail.ts (Fristen table cell)
- frontend/src/client/views/shape-list.ts (generic rule column)
- frontend/src/client/i18n.ts + i18n-keys.ts (DE+EN delta)
- frontend/src/deadlines-new.tsx (strip dropdown+sort, add toggle)
- frontend/src/deadlines-detail.tsx (Auto/Custom edit slots)
- frontend/src/styles/global.css (rule-mode + rule-label families)

internal/models/models.go

@@ -313,6 +313,14 @@ type Deadline struct {
 	// changes to paliad.deadline_rules and accepts citations from
 	// outside that table.
 	RuleCode        *string    `db:"rule_code"         json:"rule_code,omitempty"`
+	// CustomRuleText holds the lawyer's free-text rule label when the
+	// deadline form is in Custom mode (t-paliad-258 / m/paliad#89).
+	// Mutually exclusive with RuleID at the application layer: the Auto
+	// path sets RuleID and leaves this NULL; the Custom path sets this
+	// and leaves RuleID NULL. Display surfaces prefer the joined
+	// deadline_rules.name when RuleID is set, else fall back to this
+	// text + a "Custom" badge.
+	CustomRuleText  *string    `db:"custom_rule_text"  json:"custom_rule_text,omitempty"`
 	Status          string     `db:"status"            json:"status"`
 	CompletedAt     *time.Time `db:"completed_at"      json:"completed_at,omitempty"`
 	CalDAVUID       *string    `db:"caldav_uid"        json:"caldav_uid,omitempty"`