[TheGreatAxios]

Summary

The portal's Merge button now goes through the same merge gate as Triage's own merge. Before merging, the hub reads the head's CI, each reviewer's latest review and the open review threads, and refuses with 409 merge_refused and the gate's reason when a reviewer requests changes, a person's thread is open or CI has not passed. Bypassing the gate is left to a GitHub admin on GitHub.

• The GitHub executor's gate reads move into readMergeGate in @corbits/github-tool/do, used by both the executor and the hub route.
• Whether CI is optional comes from the repository's policy through mergesWithoutCi, now shared with the plan's merge step.
• The portal already shows a route's error message, so apps/web is unchanged.
• Bitbucket has no portal merge route; its merges run through the executor, which already uses the gate.
• User Manual: one sentence on the pane's Merge. docs/ARCHITECTURE.md does not mention the portal merge.

Verification

• New test in github-read-access.postgres.test.ts: a merge with changes requested, and one with failing CI, each answer 409 merge_refused and nothing is merged. It failed on main (github_failed from the merge call) and passes here.
• bun run check, bun run lint, and the hub test, github-tool do.test.ts and triage-workflows actions.test.ts pass.

Closes CL-12170

[linear-code]

CL-12170

[corbits-triage]

Triage: Pass

No changes needed from you. A maintainer will review this pull request.

Notes:

• Risk: medium (3 recently fixed files)

[corbits-triage]

No defects reported.