fix(ws): wire topicLimiter into hand-rolled test hubs

newEmitTestHub and NewHubForTest built raw Hub literals without the
topic rate limiter, so deliverBroadcast panicked on a nil receiver and
TestEmitEvents_ChannelEvent_CallsBroadcastToChannel could never pass.
CI never surfaced it because the pipeline died at govulncheck first.
Wire the limiter exactly as NewHub does; no production nil-guard, since
a nil limiter in production would silently disable rate limiting.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Server/ws/emit_test.go

@@ -34,6 +34,7 @@ func newEmitTestHub() *Hub {
 		pubsub:          NewPubSub(),
 		replayBuf:       NewEventRingBuffer(100),
 		voiceKeyHolders: make(map[int64]int64),
+		topicLimiter:    NewTopicRateLimiter(topicRateLimitPerSecond, time.Second),
 	}
 }
 

Server/ws/export_test.go

@@ -93,8 +93,9 @@ func (p *LiveKitProcess) SetProcessStoppedForTest() {
 // NewHubForTest creates a minimal Hub with no DB or limiter for webhook testing.
 func NewHubForTest() *Hub {
 	return &Hub{
-		clients: make(map[int64]*Client),
-		pubsub:  NewPubSub(),
+		clients:      make(map[int64]*Client),
+		pubsub:       NewPubSub(),
+		topicLimiter: NewTopicRateLimiter(topicRateLimitPerSecond, time.Second),
 	}
 }