Add a button to spotlight a video feed

src/app/voice.ts

@@ -88,6 +88,13 @@ export const participantPubkeyMap = writable<Map<string, Pubkey>>(new Map())
 /** Bumps when remote video is subscribed/unsubscribed so layout/video UI can react. */
 export const videoCallLayoutRevision = writable(0)
 
+/** Spotlight tile id — must match VideoCallContent `tileKey` (identity + source, not trackSid). */
+export const videoPrimaryTileKey = writable<string | undefined>(undefined)
+
+export const toggleVideoPrimaryTile = (key: string) => {
+  videoPrimaryTileKey.update(k => (k === key ? undefined : key))
+}
+
 const bumpVideoCallLayoutRevision = () => videoCallLayoutRevision.update(n => n + 1)
 
 const addParticipant = (identity: string) => {
@@ -206,6 +213,7 @@ const setUpMicrophone = async (
 
 const onRoomDisconnected = (reason?: DisconnectReason) => {
   videoCallLayoutRevision.set(0)
+  videoPrimaryTileKey.set(undefined)
   currentVoiceSession.set(undefined)
   if (reason !== undefined && reason !== DisconnectReason.CLIENT_INITIATED) {
     voiceState.set(VoiceState.Disconnected)
@@ -372,6 +380,7 @@ export const leaveVoiceRoom = async () => {
 
   voiceState.set(VoiceState.Disconnected)
   videoCallLayoutRevision.set(0)
+  videoPrimaryTileKey.set(undefined)
   currentVoiceSession.set(undefined)
   session.room.disconnect()
   speakingParticipants.set([])