fix(styles): dark-mode contrast on lime-active chips (t-paliad-291)

Six surfaces paired a lime background with var(--color-text), which
flips to cream in dark mode and collapses contrast on the high-luminance
brand lime. Switch them to var(--color-accent-dark) — the design token
already defined to stay midnight in both themes as the WCAG-AA fg on
lime.

Affected:
  - .event-card-choices-option--active  (Berufung durch … popover —
    m's primary report on m/paliad#123)
  - .fristen-row.is-active .fristen-row-num
  - .form-hint-badge
  - .paliadin-widget-send-btn
  - .smart-timeline-anchor-submit
  - .admin-rules-chip.active

Lime hue and non-active states untouched.

Refs: m/paliad#123

frontend/src/styles/global.css

@@ -1917,7 +1917,11 @@ input[type="range"]::-moz-range-thumb {
 .fristen-row.is-active .fristen-row-num {
     background: var(--color-accent);
     border-color: var(--color-accent);
-    color: var(--color-text, #111);
+    /* Lime is high-luminance; foreground stays midnight in both themes via
+       --color-accent-dark (light: midnight by default, dark: midnight
+       explicit). Using --color-text here would flip to cream in dark mode
+       and collapse contrast on lime. */
+    color: var(--color-accent-dark);
 }
 
 .fristen-row.is-prefilled .fristen-row-num {
@@ -3578,7 +3582,10 @@ input[type="range"]::-moz-range-thumb {
 .event-card-choices-option--active {
     background: var(--color-accent, #c6f41c);
     border-color: var(--color-accent, #c6f41c);
-    color: var(--color-text);
+    /* Foreground stays midnight in both themes — --color-text would flip
+       to cream in dark mode and leave the active "Berufung durch …"
+       chip unreadable on lime (m/paliad#123). */
+    color: var(--color-accent-dark);
     font-weight: 600;
 }
 
@@ -7992,7 +7999,7 @@ dialog.modal::backdrop {
     padding: 0.05rem 0.45rem;
     border-radius: 999px;
     background: var(--color-accent);
-    color: var(--color-text);
+    color: var(--color-accent-dark);
     font-size: 0.7rem;
     font-weight: 700;
     letter-spacing: 0.04em;
@@ -15922,7 +15929,7 @@ dialog.quick-add-sheet::backdrop {
     border-radius: 6px;
     border: 1px solid var(--color-border-strong);
     background: var(--color-accent);
-    color: var(--color-text);
+    color: var(--color-accent-dark);
     cursor: pointer;
     transition: background 120ms ease;
 }
@@ -16530,7 +16537,7 @@ dialog.quick-add-sheet::backdrop {
 .smart-timeline-anchor-submit {
     background: var(--color-accent, #c6f41c);
     border: 1px solid var(--color-accent, #c6f41c);
-    color: var(--color-text, #333);
+    color: var(--color-accent-dark);
     padding: 0.25rem 0.75rem;
     border-radius: 4px;
     cursor: pointer;
@@ -17468,7 +17475,7 @@ dialog.quick-add-sheet::backdrop {
 .admin-rules-chip.active {
   background: var(--color-accent, #BFF355);
   border-color: var(--color-accent, #BFF355);
-  color: var(--color-text, #000);
+  color: var(--color-accent-dark);
 }
 
 .admin-rules-pill {