Slow reconnect after extended outages + missing ParticipantConnected on agent rejoin

[ansh-tan]

Voice-agent product on LiveKit Cloud + Flutter SDK. Controlled Android outage tests (5s / 25s / 84s) surfaced two issues.

1. SDK ignores app-layer connectivity signal

Our OS connectivity monitor detects internet back before the SDK does, on longer outages where its backoff has grown:

Outage	App sees net back	SDK TRANSPORT RESTORED	Delta
~5s	18:44:20.542	18:44:20.077	SDK −0.47s
~25s	18:45:24.178	18:45:25.026	App +0.85s
~84s	18:47:17.834	18:47:18.660	App +0.83s

Ask: a room.hintReconnectNow() (or Stream<bool> at construction) that collapses the SDK's current backoff. No-op if already healthy. Not a replacement for the SDK's retry logic — just a hint.

2. ParticipantConnected not fired when same agent rejoins

On same-room reconnect, SDK fires TrackSubscribed but not ParticipantConnected:

18:44:20.499  Audio track subscribed during reconnecting — treating as ParticipantConnected
18:45:25.200  Audio track subscribed during reconnecting — treating as ParticipantConnected

Both were successful rejoins of the same agent identity. On a new-room reconnect (different identity), ParticipantConnected fires normally — so the event works for fresh participants but not rejoined ones.

Ask: intended or bug? If intended, docs for ParticipantEvent.participantConnected should say so.

Repro

1. Room with agent attached, confirm initial ParticipantConnected
2. Airplane mode on 25s, off
3. Observe: TRANSPORT RESTORED ~800ms after OS reports network; TrackSubscribed for rejoined agent but no ParticipantConnected