Fonos v0.7.2

This release is all about Linux.

• Quitting actually quits — tray "Quit Fonos" used to leave the process alive with a frozen pill stuck on screen; windows now vanish immediately and the process is guaranteed to exit.
• No more overlapping pills — on X11 the pill's old frame could stay composited under the new one on every state change; Linux now forces the same redraw pass macOS always had.
• Every recipe hotkey now works on Linux — not just the two dictation keys: the pill key, dictation hold/toggle, and any hotkey you bind in Workbench (translate selection, explain selection, …) all run through the same workflow engine as macOS. Rebinds apply without a restart, and kill -USR2 now genuinely toggles dictation (the documented Wayland fallback was previously a no-op).
• Hotkey dictation no longer runs legacy code — it used to drive a pre-engine pipeline that could wedge the pill at "Processing"; that path is retired entirely.
• Apple Speech stops pretending on Linux — picking it produced silent empty transcriptions; it now shows a clear error and is no longer offered where it can't work.
• Auto-update comes to Linux — the new AppImage updates in place from Settings → General, exactly like macOS. deb/rpm installs get a "download from GitHub" pointer instead. AppImage is now the recommended Linux install.

macOS (Apple Silicon) updates in-app; Linux: AppImage above (auto-updating), deb/rpm below.