Add Expert Mode debug screen for raw getevent output (#2081)

[keymapper-ai]

Summary

Implements #2081 — adds a debug screen accessible from Settings > Debugging that displays raw getevent output via the system bridge.

• Loads device info on open: runs getevent -il automatically when Expert Mode is connected, showing all input devices
• Record/stop: a FAB (red when recording) starts getevent -lt in the background; tapping stop kills the process and appends captured events to the output
• Bottom app bar actions: back, copy to clipboard, save/share to file, and clear
• Expert Mode gate: shows an informational card with a "Setup Expert Mode" button when the system bridge is not connected
• Monospace output: text is rendered in a scrollable, selectable, monospace font and auto-scrolls to the bottom as new output arrives

Files changed

File	Change
base/.../debug/GetEventViewModel.kt	New — HiltViewModel managing state, shell execution, clipboard, file sharing
base/.../debug/GetEventScreen.kt	New — Compose screen with top bar, content area, bottom bar
base/.../navigation/NavDestination.kt	Added GetEvent destination
base/.../BaseMainNavHost.kt	Registered GetEvent composable route
base/.../settings/SettingsViewModel.kt	Added onGetEventClick() navigation handler
base/.../settings/SettingsScreen.kt	Added "Expert Mode debug" button in Debugging section
base/.../res/values/strings.xml	Added getevent-related strings

Test plan

• Navigate to Settings > Debugging — "Expert Mode debug" entry appears
• Tap it → screen opens showing a loading indicator, then populates with getevent -il device list
• Press record FAB → button turns red/stop, getevent -lt events stream in
• Press stop → recording ends, events appended to output
• Press clear → output is cleared
• Copy button → output placed in clipboard
• Save button → Android share sheet appears
• Back button → returns to Settings
• With Expert Mode disabled → informational card shown with "Setup Expert Mode" button