Guard Android CallStyle notifications against empty caller names

[Copilot]

Android foreground call notifications were crashing when the call peer name was null/blank. NotificationCompat.CallStyle.forOngoingCall(...) requires a Person with a non-empty name and throws IllegalArgumentException otherwise.

• Crash containment

  • In OngoingCallNotification.build(), introduced a sanitized local safePeerName.
  • Fallback behavior: null or whitespace-only peerName now resolves to "unavailable".

• CallStyle path hardening (API 28+)

  • Person.Builder().setName(...) now uses safePeerName so CallStyle.forOngoingCall(...) always receives a valid person name.

• Consistency for non-CallStyle path

  • Legacy notification content text (setContentText) now also uses safePeerName to keep display behavior aligned across API levels.

String safePeerName = peerName;
if (safePeerName == null || safePeerName.trim().isEmpty()) {
    safePeerName = "unavailable";
}

Person callerPerson = new Person.Builder()
        .setName(safePeerName)
        .setImportant(true)
        .build();

[WesUnwin]

@copilot remove all iOS related changes from this PR.

[Copilot]

@copilot remove all iOS related changes from this PR.

Done in commit 4584668. All iOS-related changes were removed from this PR.

[Copilot]

Pull request overview

This PR hardens Android ongoing-call foreground notifications against crashes when the peer/caller name is null or blank, ensuring NotificationCompat.CallStyle.forOngoingCall(...) always receives a Person with a valid non-empty name.

Changes:

• Introduces safePeerName in OngoingCallNotification.build() with a fallback to "unavailable" when the provided peerName is null or whitespace-only.
• Uses safePeerName when building the Person for CallStyle notifications (API 28+ path).
• Uses safePeerName in the legacy (non-CallStyle) notification content text to keep behavior consistent across API levels.

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