feat(app): restore Settings "Check for Updates" button; solid dark-gray overlay pill

[alexkroman]

Settings — restore "Check for Updates"

Re-adds the Check for Updates button to the Advanced pane (dropped in dc6bff0). An "Updates" section shows the running version and a button that runs the shared UpdateCheckModel and reports the result in a modal — the same check reachable from the app menu and menu-bar item, all sharing the one controller. Restores UpdateCheckModel.currentVersionText and the settings.update.check UITest identifier.

Under UI testing the check is stubbed offline (UITestUpdateTransport + UpdateCheckModel.uiTest()) to always report up-to-date, so the new testCheckForUpdatesShowsResultAlert exercises the button → result-sheet flow deterministically without reaching GitHub.

Overlay — solid dark-gray pill (no Liquid Glass)

The pill body was .glassEffect(.regular.tint:) — an adaptive material that samples the backdrop to pick its light/dark rendering, and can't do so until it's composited on screen. Fading in from alpha 0, it flashed white for a frame over a dark desktop before settling dark; over a light desktop the light default ≈ the settled light, so it looked stable — the asymmetry that surfaced the bug.

Replaced it with a solid, opaque dark-gray capsule. A fixed fill never adapts, so the pill fades in the same dark gray on any backdrop with no flash. Every state is the same dark gray except .error, which keeps a red body as an alarm cue.

Drops the now-unused glassCapsuleCompat helper. Liquid Glass stays for the prominent buttons (glassButtonStyleCompat) — those never had the flash problem and using glass there is the native macOS 26 idiom.

Verification

• scripts/check.sh green (exit 0).
• testCheckForUpdatesShowsResultAlert and testOverlayPillTracksDictation pass.
• Dev build runs clean.
• The pill is now a settled state (not a transient flash), so it's easy to eyeball: run a dictation and the pill is a consistent dark gray on any background, red on error.

🤖 Generated with Claude Code