Add MCP server authentication and update Docker configuration

This commit implements several key improvements to the GeoGuessr MCP server:

## MCP Server Authentication
- Add Bearer token authentication for MCP server access control
- New middleware in src/geoguessr_mcp/middleware/auth.py
- Configuration via MCP_AUTH_ENABLED and MCP_API_KEYS environment variables
- Support for multiple API keys (comma-separated)
- Optional authentication - can be disabled for trusted deployments
- Clients connect using Authorization: Bearer YOUR_API_KEY header

## Docker Configuration Updates
- Update to use official pre-built image: nyxiumyuuki/geoguessr-mcp:latest
- Remove DOCKER_USERNAME and IMAGE_TAG from environment variables
- Simplify docker-compose.yml and docker-compose.prod.yml
- Remove healthcheck configuration (not necessary for the deployment)

## Deployment Improvements
- Move deploy.sh to scripts/deploy.sh for better organization
- Update deploy.sh to use official Docker image
- Add authentication validation in deployment script
- Improve deployment logging and error messages

## Documentation Updates
- Update README.md with authentication configuration examples
- Add MCP server authentication section with setup instructions
- Update environment variables table
- Simplify deployment instructions
- Update CLAUDE.md with new authentication architecture
- Add .env.example configuration for MCP authentication

## Technical Details
- Authentication middleware integrates with FastMCP's Starlette ASGI app
- Middleware validates Bearer tokens on all requests except /health
- Logs authentication attempts and failures
- Returns proper 401/403 HTTP status codes
- Validates configuration on startup to prevent misconfiguration

Resolves TODO items:
- [x] Fix Docker username in compose files and env vars
- [x] Add authentication to MCP server to allow access only to specific users

docker-compose.yml

@@ -1,11 +1,13 @@
 services:
   geoguessr-mcp:
-    # Option 1: Build locally
-    build:
-      context: .
-      dockerfile: Dockerfile
-    # Option 2: Use pre-built image from Docker Hub (uncomment to use)
-    # image: ${DOCKER_USERNAME:-yourusername}/geoguessr-mcp:${IMAGE_TAG:-latest}
+    # Option 1: Build locally (for development)
+    # build:
+    #   context: .
+    #   dockerfile: Dockerfile
+
+    # Option 2: Use pre-built image from Docker Hub (recommended)
+    image: nyxiumyuuki/geoguessr-mcp:latest
+
     container_name: geoguessr-mcp-server
     restart: unless-stopped
     ports:
@@ -15,12 +17,6 @@ services:
     volumes:
       # Persist schema cache between restarts
       - geoguessr-schemas:${SCHEMA_CACHE_DIR:-/app/data/schemas}
-    healthcheck:
-      test: [ "CMD", "curl", "-f", "http://localhost:${MCP_PORT:-8000}/health" ]
-      interval: 30s
-      timeout: 10s
-      retries: 3
-      start_period: 15s
     logging:
       driver: "json-file"
       options: