feat: enable Fischerei, Sitzungsprotokolle, Verbandsverwaltung modules

- Enable all 3 modules via NEXT_PUBLIC_ENABLE_* build args + runtime env
- Fix empty-string-to-null for date/optional columns in all module APIs:
  fischerei (24 fixes), verbandsverwaltung (15 fixes), sitzungsprotokolle (2 fixes)
- CACHE_BUST=12 for full rebuild with new feature flags

docker-compose.yml

@@ -335,6 +335,9 @@ services:
       NEXT_PUBLIC_ENABLE_TEAM_ACCOUNTS_BILLING: "false"
       NEXT_PUBLIC_ENABLE_PERSONAL_ACCOUNT_BILLING: "false"
       NEXT_PUBLIC_ENABLE_NOTIFICATIONS: "true"
+      NEXT_PUBLIC_ENABLE_FISCHEREI: "true"
+      NEXT_PUBLIC_ENABLE_MEETING_PROTOCOLS: "true"
+      NEXT_PUBLIC_ENABLE_VERBANDSVERWALTUNG: "true"
 
 volumes:
   supabase-db-data: