Add a master 'Enable notifications' switch that requests POST_NOTIFICATIONS
before turning on (default off, per-type toggles gated on it) and reconciles
to off if the OS permission is revoked. Add a Camera access permission tile.
Only the ongoing background-connection notice is shown without opt-in, so the
app stays reachable once notifications are granted. Wire permission_handler
and declare CAMERA.

Add a final onboarding step that requests POST_NOTIFICATIONS and, on grant,
turns on the notifications master setting so highlights, private messages and
the background-connection notice work without a trip to Settings.

Add Firebase (core/analytics/crashlytics/app_check) with App Check Play
Integrity (debug provider in debug). Analytics and Crashlytics collection are
off by default and gated behind an analyticsConsent setting; a consent toggle
lives in Settings and onboarding, and the app applies it on load. Uncaught
errors are chained into Crashlytics alongside the existing email crash
reporter. Update privacy copy to describe the opt-in telemetry.

Adding the CAMERA runtime permission made Google Play imply a required camera
feature and drop ~418 camera-less devices (Android Auto, some TVs/tablets).
Declare camera/autofocus/any as not required since capture is optional.

Preserve mounted session state while locked, reuse recent local auth,
dedupe channel tabs by IRC casefolding, and bump to 1.0.5+8.