Show Wrap-up guidance in the VS Code status bar and tooltip

[jsmestad]

What

When HeadsDown detects end-of-day time pressure, the VS Code extension should visibly show that Wrap-up is active and how much time remains. Users should be able to understand current pacing guidance without opening external tools.

Why

If Wrap-up is active but invisible, users and agents will miss the behavior change and trust drops. Clear visibility makes the feature understandable, reduces surprise, and reinforces completion-before-leaving behavior.

Acceptance Criteria

1. When the availability payload includes active wrap-up guidance, the status bar text shows a Wrap-up indicator and remaining minutes.
2. The status bar tooltip includes wrap-up state, deadline, and the active profile (normal or wrap_up) in plain language.
3. When wrap-up is not active, no Wrap-up indicator is shown and existing status behavior remains unchanged.
4. Realtime subscription updates and polling fallback both refresh Wrap-up UI state correctly within one refresh cycle.
5. Unit tests cover active, inactive, and transition states for status bar rendering.

Developer Notes

Approach: Extend the extension state model to carry wrapUpGuidance from SDK availability responses, then render it in StatusBarManager without changing existing mode semantics.

Steps:

1. Extend SDK availability usage in the extension to read wrap-up fields.
   • Files: src/extension.ts, src/status-bar.ts
2. Add status bar and tooltip rendering rules for wrap-up state.
   • Files: src/status-bar.ts
3. Add test coverage for rendering logic and state transitions.
   • Files: test/* (status bar related tests)

Testing:

• Simulate availability responses with wrap-up active and inactive.
• Verify output text and tooltip content for each mode.
• Verify behavior under polling and subscription-driven refresh.

[jsmestad]

Dependency note: this ticket depends on the shared Finish Today (Wrap-up Guidance) API/SDK contract in https://github.com/headsdownapp/heads_down/issues/812. Implementation should start after that contract lands (or behind feature-flagged SDK prerelease).