[Bug] Voice overlay orb disappears behind fullscreen applications #528

Summary

The voice dictation overlay orb (NSPanel on macOS) becomes invisible when a fullscreen application is in the foreground. Users cannot see recording/transcription status while working in fullscreen apps.

Problem

• The overlay orb displays correctly over normal (windowed) applications
• When a fullscreen app is focused (e.g., fullscreen browser, IDE, terminal), the orb is hidden behind the fullscreen window
• Users lose visual feedback for voice dictation state (listening, transcribing, error) while in fullscreen mode

Steps to reproduce

1. Enable voice dictation
2. Enter fullscreen mode in any application (e.g., Safari, VS Code, Terminal)
3. Trigger Fn push-to-talk
4. Observe: no overlay orb visible — no visual indication of recording state

Expected behavior

The overlay orb should remain visible on top of fullscreen applications, similar to how macOS system indicators (volume, brightness) overlay fullscreen content.

Possible approach

The Swift overlay helper likely needs its NSPanel window level set to a level above fullscreen windows (e.g., NSWindow.Level.screenSaver or NSWindow.Level.statusBar) and/or the collectionBehavior should include .canJoinAllSpaces and .fullScreenAuxiliary.

Environment

• macOS (Tauri desktop app with Swift overlay helper)