Validate remote-verify QR before persisting account state

[thomasbuilds]

Hardens the Stage.EnableRemoteVerify branch of the QR scan result handler in AttestationActivity so that a malformed account QR can no longer crash the app or leave remote verification in a half-enabled state.

Problem

In AttestationActivity.java the handler did:

PreferenceManager.getDefaultSharedPreferences(this).edit()
        .putLong(RemoteVerifyJob.KEY_USER_ID, Long.parseLong(values[1]))
        .putString(RemoteVerifyJob.KEY_SUBSCRIBE_KEY, values[2])
        .apply();
try {
    RemoteVerifyJob.schedule(this, Integer.parseInt(values[3]));
    snackbar.setText(R.string.enable_remote_verify_success).show();
} catch (final NumberFormatException e) {
    snackbar.setText(R.string.scanned_invalid_account_qr_code).show();
}

Two issues:

1. Long.parseLong(values[1]) is outside the try. Any QR of the form attestation.app <non-numeric> … triggers an uncaught NumberFormatException in the ActivityResultLauncher lambda and crashes the activity. Only the interval field was guarded.
2. The user id and subscribe key are written to SharedPreferences before the interval is parsed and the job is scheduled. If the interval is malformed, the prefs are already persisted, so:
   • RemoteVerifyJob.isEnabled() returns true, hiding the "Enable remote verification" button in onResume().
   • RemoteVerifyJob.isScheduled() returns false — no job runs.
   • The user has to use the "Disable remote verification" menu item to recover.

Fix

Parse both userId and interval inside a single try / catch (NumberFormatException). Only after both parse successfully are preferences committed and the job scheduled. Behavior on a valid QR is unchanged.