Current MCP clients (OpenCode, Claude, ...) only speak Streamable HTTP: they
POST JSON-RPC to the configured URL, so a legacy SSE endpoint answers
405 Method Not Allowed and not a single tool can be reached.
Run FastMCP's http_app (build_app()) under uvicorn instead of mcp.run(sse):
the MCP endpoint is now /mcp, and the custom GET /health route keeps serving
the Kubernetes probes.
Add transport tests asserting /mcp and /health are exposed and /sse is gone.
