refactor(shared-help): extract shared translations, add Zitare + Mukke help pages

- Add defaultTranslationsDE/EN and getHelpTranslations() to shared-help-ui
  so apps only need to override the subtitle instead of duplicating ~80 lines
- Refactor all 6 existing help pages to use getHelpTranslations()
  (Contacts, Calendar, Todo, Storage, Chat, Picture)
- Add help page to Zitare (FAQ, features, contact — no shortcuts)
- Migrate Mukke from custom SettingsPage-based help to shared HelpPage
  (FAQ with audio formats, lyrics editor, playlists; features; shortcuts)

All 8 web apps now use the unified shared help system.

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

packages/shared-help-ui/src/index.ts

@@ -18,6 +18,13 @@ export { default as ChangelogEntry } from './components/ChangelogEntry.svelte';
 export { default as ContactSection } from './components/ContactSection.svelte';
 export { default as HelpSearch } from './components/HelpSearch.svelte';
 
+// Default translations
+export {
+	defaultTranslationsDE,
+	defaultTranslationsEN,
+	getHelpTranslations,
+} from './translations.js';
+
 // Types
 export type {
 	HelpPageProps,