feat(ui): expose MCP discovery state in integrations

[daryllimyt]

Summary

• expose MCP discovery state, catalog counts, last successful discovery time, and redacted error summaries in the integrations UI
• add an explicit MCP integration refresh API and frontend mutation hook
• reset MCP discovery state back to pending when refresh is requested or discovery-affecting integration config changes

Related Issues

• ENG-1323

Steps to QA

1. Run TRACECAT__SERVICE_KEY=test-service-key TRACECAT__DB_ENCRYPTION_KEY='Su3XazJf5Q9PexP8MaqkOawxaggUY8ailqXFz3vGN9w=' uv run pytest tests/unit/test_mcp_integrations.py -q
2. Run uv run ruff check tracecat/integrations/service.py tracecat/integrations/router.py tests/unit/test_mcp_integrations.py
3. Run uv run basedpyright tracecat/integrations/service.py tracecat/integrations/router.py tests/unit/test_mcp_integrations.py
4. Run pnpm -C frontend check
5. Run pnpm -C frontend run typecheck

[daryllimyt]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat(agent): improve local MCP runtime failure logs #2282
• feat(ui): expose MCP discovery state in integrations #2281 👈 (View in Graphite)
• feat(mcp): queue local stdio artifact execution #2280
• feat(mcp): route remote artifact calls through user client #2279
• feat(mcp): add persisted artifact wrapper operations #2278
• feat(mcp): add catalog authorization policy service #2276
• feat(rbac): sync mcp catalog scopes #2272
• feat(mcp): persist integration discovery catalog state #2269 : 1 other dependent PR (#2270 )
• main

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[cubic-dev-ai]

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