fix: align frontend API calls with backend routes and types

- Backend: rename routes /mealplan→/mealplans, /shoppinglist→/shopping
- Backend: simplify swap/reroll to entry-centric endpoints (by entryId)
- Frontend: fix all interfaces to use string GUIDs instead of numbers
- Frontend: fix field names (weekStart, date, totalAmount) to match backend JSON
- Frontend: shopping toggle by itemName instead of non-existent id
- Frontend: handle 204 No Content on DELETE responses
- Docker-compose: use env vars for DB credentials

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

docker-compose.yml

@@ -1,13 +1,12 @@
-version: '3.8'
 services:
   app:
     build: .
     ports:
       - "3000:80"
     environment:
-      - ConnectionStrings__DefaultConnection=Host=host.docker.internal;Port=54320;Database=mealplanner;Username=mika;Password=${SHARED_POSTGRES_PASSWORD}
+      - ConnectionStrings__DefaultConnection=Host=${DB_HOST:-host.docker.internal};Port=${DB_PORT:-5432};Database=mealplanner;Username=${DB_USER};Password=${DB_PASSWORD}
       - Zitadel__Issuer=https://auth.kuns.dev
       - Zitadel__ClientId=${ZITADEL_CLIENT_ID}
-      - AllowedOrigin=http://localhost:3000
+      - AllowedOrigin=${ALLOWED_ORIGIN:-https://essen.kuns.dev}
       - ASPNETCORE_URLS=http://+:5000
       - ASPNETCORE_ENVIRONMENT=Production