fix: QA audit — lint cleanup, i18n fixes, module visibility, sidebar UX

- Fix 97 lint errors → 0 (unused imports, params, variables across 40+ files)
- Fix i18n key format: colon → dot notation for next-intl compatibility
- Add missing i18n keys (routes.application, routes.home, confirm)
- Fix module visibility: sidebar now respects per-account DB features
- Fix inject function: use dot-notation keys, add collapsed:true defaults
- Fix ConfirmDialog: use useTranslations instead of hardcoded German defaults
- Fix events page: replace placeholder 'Beschreibung' with proper description
- Fix Dockerfile: add NEXT_PUBLIC_CI ARG for Docker builds
- Collapse secondary sidebar sections by default for cleaner UX

Dockerfile

@@ -13,6 +13,7 @@ ENV NEXT_TELEMETRY_DISABLED=1
 
 # NEXT_PUBLIC_* vars are baked into the Next.js build at compile time.
 # Pass them as build args so the same Dockerfile works for any environment.
+ARG NEXT_PUBLIC_CI=false
 ARG NEXT_PUBLIC_SITE_URL=https://myeasycms.de
 ARG NEXT_PUBLIC_SUPABASE_URL=http://localhost:8000
 ARG NEXT_PUBLIC_SUPABASE_PUBLIC_KEY
@@ -20,6 +21,7 @@ ARG NEXT_PUBLIC_DEFAULT_LOCALE=de
 ARG NEXT_PUBLIC_ENABLE_FISCHEREI=true
 ARG NEXT_PUBLIC_ENABLE_MEETING_PROTOCOLS=true
 ARG NEXT_PUBLIC_ENABLE_VERBANDSVERWALTUNG=true
+ENV NEXT_PUBLIC_CI=${NEXT_PUBLIC_CI}
 ENV NEXT_PUBLIC_SITE_URL=${NEXT_PUBLIC_SITE_URL}
 ENV NEXT_PUBLIC_SUPABASE_URL=${NEXT_PUBLIC_SUPABASE_URL}
 ENV NEXT_PUBLIC_SUPABASE_PUBLIC_KEY=${NEXT_PUBLIC_SUPABASE_PUBLIC_KEY}