fix: address PR #587 REQUEST_CHANGES for MCP namespace health (#543)

- Distinguish client_namespace vs offline_spawn probe sources; only IDE
  client probes prove namespace health and feed mutation gates.
- Record assessments in session; gate gitea_submit_pr_review and
  gitea_merge_pr when client-namespace health is unhealthy/non-proven.
- Mark test_mcp_conn.py offline-only; align recovery docs to client
  reconnect (no PID-kill/config-touch as canonical recovery).
- Rebase onto current master so #590 ledger isolation keeps
  TestMergePR.test_unknown_profile_blocks green.

tests/conftest.py

@@ -66,6 +66,7 @@ def _reset_mutation_authority(monkeypatch):
     monkeypatch.setattr(mcp_server, "_MUTATION_AUTHORITY", None)
     monkeypatch.setattr(mcp_server, "_IDENTITY_CACHE", {})
     monkeypatch.setattr(mcp_server, "_REVIEW_DECISION_LOCK", None)
+    monkeypatch.setattr(mcp_server, "_LIVE_NAMESPACE_HEALTH", {})
     monkeypatch.setattr(mcp_server, "_preflight_whoami_called", False)
     monkeypatch.setattr(mcp_server, "_preflight_capability_called", False)
     monkeypatch.setattr(mcp_server, "_preflight_resolved_role", None)