fix(scheduler): ignore manual Strix dispatch as merge evidence

[cursor]

A caller-selected workflow_dispatch Deep run can publish the same Strix check name for up to six hours. Required merge evidence stays pull_request_target and repository_dispatch strix-scan.

What to do next

Review this slice on its own. Do not fold it into #1054 (official quick|standard|deep mapping). After this lands, a manual Deep scan on a PR head will not park, fail, or satisfy the merge scheduler.

Keep #1054 as the only mode-mapping vehicle. After exact-head quality is green there, add the doctoring residual-risk sentences on that branch.

Change

• Read checkSuite.workflowRun.event and ignore workflow_dispatch check runs in Strix merge evidence, failed-check collection, action-required, and job reruns.
• A completed required Strix check run wins over a later pending strix commit status.
• Non-central active_review_run_refs skips same-head Deep runs so they cannot return already_running and block strix-scan.
• A successful strix commit status can still supersede a failed required check.

Doctoring: docs/doctoring/strix-manual-dispatch-not-merge-evidence.md (APA 7th).

Local evidence: pytest tests/test_pr_review_merge_scheduler.py tests/test_required_workflow_queue_contract.py — 161 passed; interrogate 100% on the scheduler module.