Eliminate I/O duplication in phase classes

[devloop-bot]

Parent

Parent: #196

What to build

Remove private _comment and _cleanup methods from ExecutePhase and ReviewPhase. These duplicate the same Temporal activity-calling pattern that PhaseOps already provides through _phase_comment and _phase_cleanup.

Have phase classes call PhaseOps methods via the injectable callbacks seam instead of re-implementing activity calls. Keep only phase-specific logic (answer_questions, post_review_findings, dispatch_review).

This restores seam discipline: phases cross the seam once through PhaseOps instead of duplicating the I/O at each phase.

Acceptance criteria

• ExecutePhase no longer defines _comment or _cleanup methods
• ReviewPhase no longer defines _comment or _cleanup methods
• Both phases call PhaseOps methods for I/O operations
• Phase-specific methods (answer_questions, post_review_findings, dispatch_review) remain in their respective phases
• All existing tests still pass
• ~40 lines of duplicated I/O code removed

Blocked by

• Remove _WorkflowCommon module (cleanup) #200 (Remove _WorkflowCommon module — PhaseOps must be the sole I/O protocol first)