Feature: Add Floating Action Button (Overlay) for accessibility

[modelorona]

User Story

As a user with accessibility needs, I want a floating button on my screen that persists over other apps, allowing me to lock the device without physical buttons or gestures.

Technical Implementation Details

• Permission: Request SYSTEM_ALERT_WINDOW (Draw over other apps).
• Service: Create a foreground service to manage the floating view (WindowManager.addView).
• UI: A small, circular, semi-transparent button (FAB).
• Behavior:
  • Single tap: Lock screen (via existing Accessibility Service).
  • Long press: Move the bubble (optional but recommended) or close it.
• Settings: Add a toggle in the main app UI to enable/disable this feature.

Acceptance Criteria

• Toggle in settings to enable "Floating Button".
• Button appears over other apps (e.g., Chrome, YouTube).
• Tapping the button locks the screen.

[modelorona]

code in main, awaiting release