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/guidelines/sveltekit-web.md

@@ -818,7 +818,7 @@ All web apps with backends now use the runtime injection pattern:
 
 - ✅ `chat/apps/web`
 - ✅ `picture/apps/web`
-- ✅ `zitare/apps/web`
+- ✅ `quotes/apps/web`
 - ✅ `contacts/apps/web`
 - ✅ `calendar/apps/web`
 - ✅ `clock/apps/web`