Redesign app icon and add dedicated notification icon

[AgentStart1]

Replace the text-based launcher logo with an F-shaped wing mark in plum, off-white, and lime. Update adaptive and round launchers, all legacy density assets, the in-app logo, and the shared splash artwork; add a monochrome layer for Android themed icons.

Both service notification builders now use a dedicated white-on-transparent 24 dp drawable instead of the colored launcher icon. Add a CairoSVG regeneration script and developer instructions for the maintained PNG assets. No design preview directory is included.

Validation:

• ./gradlew :app:processDebugResources passed.
• AAPT2 compilation of app resources passed.
• Checked XML parsing, launcher PNG dimensions, adaptive safe-circle geometry, and visual previews at notification sizes.
• Regeneration script passed after removing preview generation; git diff --check passed.

Device launcher and notification rendering has not been tested on a physical device.