fix: reliable first-message send, QR routing, auto-lock recovery

Fixes reported by testers and found in an app review:

- First message right after install no longer fails. Before the app
  finished registering with the relay, the outgoing message could crash on
  a null delivery address. The profile field is now optional and the send
  path throws a clear "still connecting, try again shortly" error while
  registration completes in the background.
- The QR code and share link now appear only once the delivery address is
  ready. Previously a link generated before the first connection lacked
  routing, so the other side could not send the first message. The screen
  now shows a connecting state and reactively swaps in the QR when ready.
- Incomplete contact links are rejected on import instead of failing at
  first send, with a clear prompt to ask for a fresh link.
- Auto-lock no longer silences the app: after locking and unlocking,
  messaging is restarted (it previously stayed dead until app restart).
- Group messages are marked failed on a non-per-member send error instead
  of hanging in the "sending" state forever.
- Hardened the relay client against a rare duplicate connection when
  toggling Tor or locking mid-connect, and fromShareString now rejects a
  delivery address of the wrong length.
- Pin unifiedpush below 6.2.0 to drop the webcrypto dependency (its native
  framework lacks LC_ENCRYPTION_INFO and blocked the iOS upload).
- Skip Android release lint (network dependency check hangs on the build
  host and adds no value for a Flutter app).

app/test/crypto/identity_test.dart

@@ -133,5 +133,28 @@ void main() {
       expect(PublicIdentity.fromShareString('sepot://add/%%%'), isNull);
       expect(PublicIdentity.fromShareString(''), isNull);
     });
+
+    test('share link s routingem: aid+da přežijí roundtrip', () async {
+      final base = await LocalIdentity.create('Routovaná');
+      final withRouting = base.publicIdentity.withRouting(
+        accountId: 'deadbeef',
+        deliveryAddress: Uint8List.fromList(List.generate(32, (i) => i)),
+      );
+      final parsed =
+          PublicIdentity.fromShareString(withRouting.toShareString());
+      expect(parsed, isNotNull);
+      expect(parsed!.accountId, 'deadbeef');
+      expect(parsed.deliveryAddress,
+          Uint8List.fromList(List.generate(32, (i) => i)));
+    });
+
+    test('fromShareString: da špatné délky → null (ne vadný kontakt)', () async {
+      final base = await LocalIdentity.create('Krátká');
+      final bad = base.publicIdentity.withRouting(
+        accountId: 'deadbeef',
+        deliveryAddress: Uint8List.fromList(List.generate(8, (i) => i)),
+      );
+      expect(PublicIdentity.fromShareString(bad.toShareString()), isNull);
+    });
   });
 }