feat(registratura): add reminders section, expiry helpers, imminent actions dashboard

- Add "Remindere & Alerte" section in entry detail panel showing AC validity,
  expiry date, and tracked deadline status with color-coded indicators
- Add quick expiry date buttons (6/12/24 months from document date) in entry form
- Default dosare view to show only active threads
- Add ImminentActions dashboard component showing urgent items (expired docs,
  AC validity warnings, overdue/imminent deadlines) sorted by urgency

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/modules/registratura/components/thread-explorer.tsx

@@ -126,7 +126,7 @@ export function ThreadExplorer({
   onNavigateEntry,
 }: ThreadExplorerProps) {
   const [search, setSearch] = useState("");
-  const [activeOnly, setActiveOnly] = useState(false);
+  const [activeOnly, setActiveOnly] = useState(true);
 
   const threads = useMemo(() => buildThreads(entries), [entries]);