Add CI validation using the official MCP Python SDK

[madeinplutofabio]

Summary

The Phase 3A.2-E real-host validation gate caught a real bug (rmcp graceful-shutdown panic, fixed in #25) that the existing CI smoke did not. The fix added regression sentinels (graceful_shutdown_does_not_panic in tests/mcp_protocol.rs and the post-dialog exit-status assertion in ci_smoke.py), but those still use raw JSON-RPC. Adding an SDK-driven CI job would catch ecosystem-level regressions earlier.

Why this matters

• ci_smoke.py uses hand-crafted JSON-RPC; it does not exercise the same code paths a real MCP client does.
• An SDK-driven CI job validates the actual wire interactions adopters will see.
• The cost is small: one extra workflow job that pip-installs the SDK.

Acceptance criteria

• Add a CI job (could be a new job in .github/workflows/rust.yml or a separate workflow).
• Job installs the official MCP Python SDK (pip install mcp).
• Spawns ncp-mcp-server as a subprocess, performs initialize then tools/list then tools/call, closes stdin gracefully, asserts clean subprocess exit.
• Decide whether the job should be a required check or an advisory check. Recommend advisory initially; promote to required after a few PRs prove stability.
• Keep the existing stdlib-only ci_smoke.py as the required dependency-free check. Do not break it.

Where to read

• .github/workflows/rust.yml for the existing mcp-smoke job (template)
• examples/mcp/ci_smoke.py for the current raw-JSON-RPC smoke
• The reference SDK client used during Phase 3A.2-E validation lived in /tmp/ncp-real-host-validation.py during the publish gate (pattern reference)