fix(bin): gate merges on unresolved review feedback

[twilwa]

Summary

• gate merges on unresolved, non-outdated inline review comments and each reviewer's current changes-requested verdict
• print whole-PR conversation comments without making automated conversation noise an always-firing blocker
• add a reason-bearing, explicitly logged review-comments override while failing closed on unavailable review state
• prevent informational note status lines from triggering legacy wake tokens

Motivation

Firstmate previously merged twilwa/session-bored#166 while an unread P1 inline review comment remained, allowing a reviewer-permissions over-grant to land on main. This change makes that review surface part of the merge contract without training operators to reflexively override a gate that blocks on every automated conversation notice.

Validation

• tests/fm-pr-merge.test.sh: 24 passed
• tests/fm-watch-triage.test.sh: 49 passed
• tests/fm-pr-check-security.test.sh: 36 passed
• shell syntax checks passed
• git diff validation passed

Safety

• bot comments and severity text receive no special filtering
• resolved and API-confirmed outdated inline threads pass
• unsupported or failed resolution-state queries fail closed
• override is never inferred and requires a logged human reason