feat: add /health endpoint and switch to Streamable HTTP transport

- Switch from legacy SSE transport (sse_app) to Streamable HTTP (http_app)
  - Fixes 405 Method Not Allowed for MCP clients like Gemini CLI
  - MCP endpoint now at /mcp (POST) instead of /sse (GET)

- Add /health endpoint that bypasses MCP_ALLOWED_HOSTS validation
  - Returns {"status": "ok"} (200) or {"status": "degraded"} (503)
  - Enables Docker health checks without exposing to external hosts

- Add curl to Docker image for health checks
- Add healthcheck config to docker-compose files
- Add test-health and test-mcp Makefile targets
- Update documentation

README.md

@@ -45,14 +45,22 @@ services:
       - KOMODO_URL=https://komodo.example.com
       - KOMODO_API_KEY=your-key
       - KOMODO_API_SECRET=your-secret
-      - MCP_ALLOWED_HOSTS=komodo-mcp.example.io,localhost:*
+      - MCP_ALLOWED_HOSTS=komodo-mcp.example.io
     ports:
       - "8000:8000"
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
 ```
 
-### Connect MCP Client
+### Endpoints
 
-SSE endpoint: `https://your-host/sse`
+| Endpoint | Method | Description |
+|----------|--------|-------------|
+| `/mcp` | POST | MCP protocol endpoint |
+| `/health` | GET | Health check (bypasses `MCP_ALLOWED_HOSTS`) |
 
 ## Local Development
 
@@ -67,12 +75,12 @@ make dev
 
 # Test
 make logs
-make test-sse
+make test-mcp
 make stop
 ```
 
 ## Tech Stack
 
 - Python 3.11+ / FastMCP / httpx
-- SSE transport / uvicorn
+- Streamable HTTP transport / uvicorn
 - Docker with multi-stage build