Merge _WorkflowCommon I/O methods into PhaseOps

[devloop-bot]

Parent

Parent: #196

What to build

Consolidate the five I/O operation methods (_comment, _dispatch, _cleanup, _request_reviewer, _emit_kpis) from _WorkflowCommon into PhaseOps, where they become methods that use the existing injectable callback fields. This eliminates the duplicate I/O protocol that DevLoopWorkflow and PRCommentWorkflow currently inherit through _WorkflowCommon.

The PhaseOps methods should follow the same pattern as the existing _phase_comment / _phase_cleanup: use injectable callbacks when available, fall back to Temporal activity calls otherwise. This is the foundation that makes the subsequent inheritance cleanup safe.

Acceptance criteria

• PhaseOps has methods for _comment, _dispatch, _cleanup, _request_reviewer, _emit_kpis that mirror _WorkflowCommon functionality
• PhaseOps methods use injectable callback fields first, fall back to Temporal activity paths
• No existing callers are changed — PhaseOps gains methods, nothing loses them
• All existing tests still pass
• PRCommentWorkflow code paths exercise the new PhaseOps methods

Blocked by

None - can start immediately

[devloop-bot]

⏳ queued — agent is working on this issue