fix: recorder widget doesn't hide when not in use (#100)

[karansinghgit]

Fixes #100.

Cause

The recorder redesign turned the pill into an always-present widget: showIdleRecorder() shows it at launch and returnToIdle() deliberately keeps it on screen. So it never disappears in either recording mode — as multiple users reported.

Fix

Restore hide-when-idle as the default, and gate the always-visible behavior behind a new opt-in setting.

• Settings → General → "Always show recorder pill" (default off):
  • Off: the recorder appears only while dictating and hides when idle.
  • On: the previous always-present pill.
• returnToIdle() now orderOut()s the panel when the toggle is off (runs after commit and after cancel / no-speech). Recording still shows the HUD via startRecording().
• showIdleRecorder() only fronts the pill at launch when the toggle is on.
• Flipping the setting posts .recorderIdleVisibilityChanged; AppDelegate observes it and calls applyIdleVisibilityPreference() to show/hide immediately (guards against hiding mid-session via the panel's interactive state).

Notes

• CI here will be red until ci: build on macos-26 so the macOS 26 SDK (.glassEffect) is available #104 (macos-26 runner) merges — pre-existing .glassEffect SDK issue, unrelated to this change.

Test plan

• Default: pill absent on launch → appears on record → hides after paste. Works in both Hold and Toggle modes.
• Turn the setting on → pill stays resting on screen; off → hides again immediately.