[mnoah1]

Summary

Adds the repair RFC and initial APIs for the workflow in #894: the FixRequest queue message, repair entities and storage interfaces, and the RepairExecutor.Submit extension.

Reuses #916’s OpenIssue (task, unit, and first-seen build) and passes it with the detecting BuildID through SubmitRequest. The initial Fix is keyed by the detecting BuildID, with request-history events for the submission claim and result. A durable submitting marker prevents redelivery from repeating the trigger. Monitoring, shared-cause decisions, additional fixes, and verified recovery are follow-up work.

Stacked on #894 (mnoah1/stovepipe-build-analysis).

Test Plan

• //stovepipe/core/messagequeue:go_default_test passed.
• //stovepipe/entity:go_default_test passed; affected fixer/storage libraries and generated mock packages built successfully.
• Passed make fmt lint check-tidy check-gazelle docs-build for the contract changes; the documentation build and Mermaid validation also passed after restacking.
• Verified the branch is exactly one commit above docs(stovepipe): outline build analysis and repair workflow #894's head.

Revert Plan

Revert the repair contracts commit.

Issue Links

None — this RFC and API layer is being prepared for team review without a linked issue.