feat: Registratura thread explorer, AC validity tracker, interactive I/O toggle + Password Vault rework

Registratura improvements:
- Thread Explorer: new 'Fire conversatie' tab with timeline view, search, stats, gap tracking (la noi/la institutie), export to text report
- Interactive I/O toggle: replaced direction dropdown with visual blue/orange button group (Intrat/Iesit with icons)
- Doc type UX: alphabetical sort + immediate selection after adding custom type
- AC Validity Tracker: full Autorizatie de Construire lifecycle workflow (12mo validity, execution phases, extension request, required docs checklist, monthly reminders, abandonment/expiry tracking)

Password Vault rework (renamed to 'Parole Uzuale' v0.3.0):
- New categories: WiFi, Portale Primarii, Avize Online, PIN Semnatura, Software, Hardware (replaced server/database/api)
- Category icons (lucide-react) throughout list and form
- WiFi QR code dialog with connection string copy
- Context-aware form (PIN vs password label, hide email for WiFi/PIN, hide URL for WiFi, hide generator for PIN)
- Dynamic stat cards showing top 3 categories by count
- Removed encryption banner
- Updated i18n, flags, config

src/core/i18n/locales/ro.ts

@@ -79,7 +79,7 @@ export const ro: Labels = {
     description: "Bibliotecă semnături digitale și ștampile scanate",
   },
   "password-vault": {
-    title: "Seif Parole",
+    title: "Parole Uzuale",
     description: "Depozit intern de credențiale partajate",
   },
   "it-inventory": {