fix(realtime): forward all caller opts from track() to send() (#1620)

## Summary

`RealtimeChannel.track()` only forwarded `timeout` to the underlying
`send()`, rebuilding the opts map as `{'timeout': opts['timeout'] ??
_timeout}` and silently dropping any other caller-supplied options. It
now forwards the full `opts` map, matching `untrack()` and the
supabase-js behavior. The timeout fallback is preserved because `send()`
already resolves `opts['timeout'] ?? _timeout`.

**Outcome:** implemented (bug-fix)

## Tests

Added a `track opts forwarding` group in `channel_test.dart` verifying
that a custom non-timeout opt, a custom timeout opt, and the empty
default all reach `send()` unchanged. Full `channel_test.dart` passes
(57 tests).

## References

- Linear: SDK-1321
- supabase-js: PR #2490 / commit `7fd2bc39`

## Compliance matrix

`realtime.presence.track` was already `implemented` with symbol
`RealtimeChannel.track`; this fix corrects its behavior without adding
new public symbols, so no matrix change was required.

Author: spydon

packages/realtime_client/lib/src/realtime_channel.dart

@@ -328,7 +328,10 @@ class RealtimeChannel {
         'event': 'track',
         'payload': payload,
       },
-      opts: {'timeout': opts['timeout'] ?? _timeout},
+      opts: {
+        'timeout': _timeout,
+        ...opts,
+      },
     );
   }
 

packages/realtime_client/test/channel_test.dart

@@ -835,6 +835,51 @@ void main() {
     });
   });
 
+  group('track opts forwarding', () {
+    late _OptsCapturingChannel capturingChannel;
+
+    setUp(() {
+      socket = RealtimeClient('', timeout: const Duration(milliseconds: 1234));
+      capturingChannel = _OptsCapturingChannel('topic', socket);
+    });
+
+    test('track forwards a custom non-timeout opt to send', () async {
+      await capturingChannel.track({'id': 123}, {'ack': true});
+
+      expect(capturingChannel.capturedOpts, containsPair('ack', true));
+    });
+
+    test('track forwards a custom timeout opt to send', () async {
+      await capturingChannel.track({'id': 123}, {'timeout': 2500});
+
+      expect(capturingChannel.capturedOpts, containsPair('timeout', 2500));
+    });
+
+    test(
+      'track falls back to the channel timeout when none provided',
+      () async {
+        await capturingChannel.track({'id': 123});
+
+        expect(
+          capturingChannel.capturedOpts,
+          containsPair('timeout', const Duration(milliseconds: 1234)),
+        );
+      },
+    );
+
+    test('track keeps custom opts alongside the default timeout', () async {
+      await capturingChannel.track({'id': 123}, {'ack': true});
+
+      expect(
+        capturingChannel.capturedOpts,
+        allOf(
+          containsPair('ack', true),
+          containsPair('timeout', const Duration(milliseconds: 1234)),
+        ),
+      );
+    });
+  });
+
   group('presence enabled', () {
     setUp(() {
       socket = RealtimeClient('', timeout: const Duration(milliseconds: 1234));
@@ -1330,3 +1375,20 @@ class _SetAuthThrowingSocket extends RealtimeClient {
     throw thrown;
   }
 }
+
+class _OptsCapturingChannel extends RealtimeChannel {
+  _OptsCapturingChannel(super.topic, super.socket);
+
+  Map<String, dynamic>? capturedOpts;
+
+  @override
+  Future<ChannelResponse> send({
+    required RealtimeListenTypes type,
+    String? event,
+    required Map<String, dynamic> payload,
+    Map<String, dynamic> opts = const {},
+  }) async {
+    capturedOpts = opts;
+    return ChannelResponse.ok;
+  }
+}