[Feat] Add CircleCI built-in integration

[roomote-roomote]

​Opened on behalf of @daniel-lxs. Follow up by mentioning @roomote-roomote, in the web UI, or in Telegram.

What changed

• Added CircleCI to the existing MCP_INTEGRATIONS registry with its official hosted streamable HTTP endpoint, deployment-scoped OAuth/DCR connection, and OAuth resource.
• Reused the existing Settings integration list and generic OAuth connection flow. Integrations.tsx continues to render directly from MCP_INTEGRATIONS; this adds no new list, section, or special UI.
• Kept diagnostic tools available while default-disabling the documented rerun_workflow and cancel_workflow mutations.
• Added the Simple Icons CircleCI mark, self-setup and Slack recommendation metadata, app URL detection, task setup guidance, focused registry tests, and public docs.

Why this change was made

CircleCI now provides an official hosted MCP server whose public metadata confirms dynamic client registration and PKCE. The integration brings CI diagnosis into tasks without exposing workflow mutations by default.

Impact

Operators can connect CircleCI once from Settings > Integrations and use run, workflow, job, log, test, artifact, and usage context from tasks. The focused catalog/self-setup/Settings tests passed, the four generic integration-placement suites passed, docs validation and broken-link checks passed, and full check-types, lint:fast, and git diff --check passed. Live OAuth consent, tool discovery, and credential-backed CircleCI calls were not performed.

Related PRs

• Cloudflare #2992
• Stripe #2995
• Buildkite #2994

[roomote-community]

No code issues found. See task

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