feat(attention): complete v0.1.2 handoff bloom

[tcballard]

Summary

Completes the v0.1.2 trustworthy-handoff contract by making a newly selected agent interruption briefly explain why and where it needs the user.

• derives only coarse, allowlisted attention reasons: approval, answer, or generic attention;
• expands the existing native status item for six seconds, then settles back to Codex needs you or Claude needs you;
• includes a sanitized project basename without adding a panel, queue, count, notification, or Perch-style attention inbox;
• keeps legacy and unknown stored events visible through the generic fallback;
• bumps v0.1.2 to build 4 and updates the release contract.

Behavior

• The first presentation after launch is settled, so an old wait never replays as a new interruption.
• Repeated polling does not extend the bloom.
• A changed item or reason starts a fresh bloom.
• Return, Snooze, Hide, or leaving the needs-you phase cancels it immediately.
• Timer expiry is generation-guarded and settlement is deferred while the context menu is tracking.
• The implementation remains one native NSStatusItem button with no custom island surface, sound, bounce, glow, or motion-dependent meaning.

Privacy

The persisted reason is derived solely from the allowlisted hook event name and notification type. Prompt text, question text, notification bodies, tool names, tool input, commands, arguments, and permission targets are neither decoded into nor retained by the session state.

Verification

• swift test — 73 tests passed with 0 failures.
• Release package built successfully with the production Swift configuration.
• The packaged app and nested helper passed strict code-sign verification.
• The running packaged app was inspected in the real macOS menu bar: the privacy-safe expanded state rendered correctly and settled after six seconds.
• Independent final review reported no blockers or high-impact findings.

Implements docs/v0.1.2-always-ready.md.