feat: add MongoDB support with connection pooling and repository pattern

docker-compose.yml

@@ -0,0 +1,33 @@
+version: "3.8"
+
+services:
+  purenotify_backend:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    ports:
+      - "3000:3000"
+    environment:
+      # These should match the defaults or your specific configuration in config.rs
+      BIND_ADDRESS: "0.0.0.0:3000"
+      MONGODB_URI: "mongodb://mongodb:27017"
+      DATABASE_NAME: "purenotify"
+      RUST_LOG: "info,tower_http=debug,mongodb=debug"
+    depends_on:
+      - mongodb
+    # Optional: If you want to enable the no-auth feature for local development
+    # command: cargo run --features "no-auth"
+
+  mongodb:
+    image: mongo:6.0
+    ports:
+      - "27017:27017"
+    volumes:
+      - mongodb_data:/data/db
+      # Optional: MongoDB authentication (highly recommended for production)
+      # MONGO_INITDB_ROOT_USERNAME: your_mongo_username
+      # MONGO_INITDB_ROOT_PASSWORD: your_mongo_password
+      # MONGODB_REPLICA_SET_NAME: rs0 # Uncomment for replica set
+
+volumes:
+  mongodb_data: