refactor: rename zitare -> quotes (Zitate)

Zitare was opaque Latin/Italian-flavored branding. Renamed to clear
English "quotes" (DE: Zitate) matching short-concrete-noun cluster.

- Module, routes, API, i18n, standalone landing app, plans dirs
- Dexie tables: quotesFavorites, quotesLists, quotesListTags,
  customQuotes (dropped redundant "quotes" prefix on the last)
- Logo QuotesLogo, theme quotes.css, search provider, dashboard
  widget QuoteWidget
- German user-facing label "Zitate" (English brand stays Quotes)

Pre-launch, no data migration needed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/plans/local-first-architecture-migration.md

@@ -325,7 +325,7 @@ Alle Web-Apps mit CRUD-Datenmodell wurden auf Local-First migriert:
 | App | Collections | Server-Logik verbleibt |
 |---|---|---|
 | **Todo** | tasks, projects, labels, taskLabels, reminders | RRULE, Reminders (Hono/Bun) |
-| **Zitare** | favorites, lists | Nur Sync |
+| **Quotes** | favorites, lists | Nur Sync |
 | **Calendar** | calendars, events | RRULE, Google Calendar OAuth |
 | **Clock** | alarms, timers, worldClocks | Nur Sync |
 | **Cards** | decks, cards | Spaced Repetition, LLM |