Rework menu bar: word count in icon, Report button in header, Check for Updates in footer

[FuJacob]

Summary

• Menu bar icon: Surface the running total of accepted (tabbed) words as a compact label next to the paw-print icon. Uses abbreviated formatting (1.2k, 3.5M) and only appears after at least one word is accepted.
• Menu header: Replace the "N words accepted" counter with the "Report Bug / Feedback" button for quicker access.
• Menu footer: Move "Check for Updates" to the footer where Report used to be.

Validation

xcodebuild -project tabby.xcodeproj -scheme tabby -destination 'platform=macOS' build
# ** BUILD SUCCEEDED **

xcodebuild -project tabby.xcodeproj -scheme tabby -destination 'platform=macOS' build-for-testing
# ** TEST BUILD SUCCEEDED **

swiftlint lint --quiet
# No new warnings (only pre-existing ones in unrelated files)

Linked issues

None.

Risk / rollout notes

• MenuBarStatusLabelView now observes SuggestionCoordinator to display the word count. The label re-renders only when the count changes.
• MenuBarView no longer depends on SuggestionCoordinator; it takes AppUpdateManager instead.