fix(nests): rotate moq-lite groups + reconnect after publisher cycle

To make a SubscribeHandle survive a publisher session swap on the same
relay, three things had to change together:

1. Broadcaster emits one Opus frame per moq-lite group
   (`publisher.send` + `publisher.endGroup`). moq-lite's "from-latest"
   subscribe semantics deliver a new subscriber the NEXT group's
   frames; without per-frame rotation a subscriber that attaches
   mid-broadcast waits forever for the (single, never-ending) group
   to end.
2. MoqLiteSession opens its announce-watch bidi synchronously before
   the first subscribe, dispatches subscribe + announce frames over a
   single long-running collector (varint type code hoisted outside
   `collect`), and FINs the publisher's currentGroup when an inbound
   subscribe bidi closes — so the next send opens a fresh group keyed
   off the live subscriber instead of the recycled one.
3. ReconnectingNestsListener no longer breaks on terminal=Closed in
   the orchestrator; the user-driven stop path goes through
   `orchestrator.cancel()`, so any other Closed (peer-driven
   transport close, half-broken session, publisher recycle) is a
   reconnect trigger.

Round-trip interop test updated to assert `groupId == idx` (one group
per frame) rather than `groupId == 0`. All three reconnecting-listener
interop scenarios now pass against the real moq-rs relay:
happy-path, session-swap, and listener-survives-publisher-recycle.

nestsClient/src/commonTest/kotlin/com/vitorpamplona/nestsclient/moq/lite/MoqLiteSessionTest.kt

@@ -79,8 +79,7 @@ class MoqLiteSessionTest {
 
             val peerHandlesSubscribe =
                 async {
-                    val bidi = serverSide.peerOpenedBidiStreams().first()
-                    val req = readSubscribeRequest(bidi)
+                    val (bidi, req) = nextSubscribeBidi(serverSide)
                     assertEquals("speakerPubkey", req.broadcast)
                     assertEquals("audio/data", req.track)
                     assertEquals(MoqLiteSession.DEFAULT_PRIORITY, req.priority)
@@ -130,8 +129,7 @@ class MoqLiteSessionTest {
 
             val peer =
                 async {
-                    val bidi = serverSide.peerOpenedBidiStreams().first()
-                    readSubscribeRequest(bidi)
+                    val (bidi, _) = nextSubscribeBidi(serverSide)
                     bidi.write(
                         MoqLiteCodec.encodeSubscribeDrop(
                             MoqLiteSubscribeDrop(errorCode = 4L, reasonPhrase = "no such broadcast"),
@@ -396,8 +394,7 @@ class MoqLiteSessionTest {
             var peerBidi: FakeBidiStream? = null
             val peer =
                 async {
-                    val bidi = serverSide.peerOpenedBidiStreams().first()
-                    readSubscribeRequest(bidi)
+                    val (bidi, _) = nextSubscribeBidi(serverSide)
                     bidi.write(MoqLiteCodec.encodeSubscribeOk(okFor(0L)))
                     peerBidi = bidi
                     // Drain whatever the listener writes after Ok — moq-lite