FCE-3368: Android ForegroundService should take a importance flag

[MiloszFilimowski]

Description

• Add optional importance?: 'low' | 'high' to ForegroundServiceConfig;
• Native: WebRTCForegroundService maps the value to NotificationChannel importance and NotificationCompat priority via channelImportanceFor / builderPriorityFor
  helpers. Defaults to 'high' when omitted (current behavior).
• Fix: tapping the notification now opens the host app's launcher activity. Previously the service Intent was passed to PendingIntent.getActivity(...), which had no
  activity component to resolve, so the tap silently did nothing.
• Switched the launcher PendingIntent to FLAG_IMMUTABLE and added FLAG_ACTIVITY_SINGLE_TOP | FLAG_ACTIVITY_CLEAR_TOP so the existing task is reused instead of
  stacked.

Motivation and Context

The foreground-service notification was always loud (IMPORTANCE_HIGH) and tapping it did nothing - both made the background-call indicator unnecessarily intrusive and
broken. Exposing importance lets consumers opt into a silent ongoing-call style, and the launcher fix restores the expected "tap to return to the app"

[linear]

FCE-3368

[Copilot]

Pull request overview

This PR extends the React Native foreground-service API to allow callers to control notification “loudness” via an importance flag, and fixes Android notification taps so they reopen the host app instead of doing nothing.

Changes:

• Added optional importance?: 'low' | 'high' to ForegroundServiceConfig and forwarded it to the native module.
• Android foreground service now maps importance to NotificationChannel importance and NotificationCompat priority (defaulting to high).
• Android notification tap now targets the app’s launcher activity via getLaunchIntentForPackage(...) with an immutable PendingIntent.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/useForegroundService.ts	Adds importance to the JS/TS config and forwards it to native.
android/src/main/java/com/oney/WebRTCModule/foregroundService/WebRTCForegroundService.java	Applies importance to notification priority/channel importance and fixes notification tap intent.
android/src/main/java/com/oney/WebRTCModule/foregroundService/ForegroundServiceController.java	Reads importance from the RN config (default high) and passes it to the service intent.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Magmusacy]

looks good to me ☕