Fix mobile validation, cascade delete for businesses/categories, and DB error handling.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -0,0 +1,23 @@
+# PostgreSQL for local development (no SSH tunnel).
+# Start: docker compose up -d
+# Stop:  docker compose down
+services:
+  postgres:
+    image: postgres:16-alpine
+    restart: unless-stopped
+    ports:
+      - '5432:5432'
+    environment:
+      POSTGRES_USER: montime
+      POSTGRES_PASSWORD: montime
+      POSTGRES_DB: montime
+    volumes:
+      - montime_pg_data:/var/lib/postgresql/data
+    healthcheck:
+      test: ['CMD-SHELL', 'pg_isready -U montime -d montime']
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+volumes:
+  montime_pg_data: