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>

scripts/mac-mini/build-landings.sh

@@ -20,7 +20,7 @@ declare -A LANDINGS=(
     ["it"]="services/it-landing"
     ["chat"]="apps/chat/apps/landing"
     ["picture"]="apps/picture/apps/landing"
-    ["zitare"]="apps/zitare/apps/landing"
+    ["quotes"]="apps/quotes/apps/landing"
     ["presi"]="apps/presi/apps/landing"
     ["clock"]="apps/clock/apps/landing"
     ["cards"]="apps/cards/apps/landing"