Fix adobe-edge web: "Session ID is not available" race on media events

[tvanlaerhoven]

Summary

On web, AdobeEdgeHandler treated trackSessionStart() as fire-and-forget: it flipped _sessionInProgress = true immediately, so any media event fired before the edge network returned a sessionId was rejected by alloy with
Failed to trigger media event: media.bitrateChange. Session ID is not available for playerId: <uuid>.

The session is now only considered active once the start is confirmed, events are queued until then, and failed starts are retried:

startSession(mediaLength, attempt, sessionMetadata?) {
  const generation = ++this._sessionGeneration;   // invalidates in-flight starts on reset/sourcechange
  this._sessionStarting = true;
  Promise.resolve(tracker.trackSessionStart(...))
    .then((result) => {
      if (generation !== this._sessionGeneration) { /* orphan: complete if needed, then end */ return; }
      if (result?.sessionId) { this._sessionInProgress = true; flush(this._eventQueue); }
      else                   { this.retryStartSession(generation, mediaLength, attempt, customMetadata); }
    })
    .catch(() => this.retryStartSession(...));     // no more unhandled rejections
}

Other behaviour worth calling out:

• maybeStartSession() is retried once the media tracker promise resolves, so a loadedmetadata that arrives before the tracker is ready no longer silently skips the session start.
• Retries: 3 attempts with 1s/2s backoff. After giving up, _sessionStartAbandoned is set and events are dropped (not queued) until a sourcechange/stopAndStartNewSession starts a fresh session.
• The custom metadata from updateMetadata() is snapshotted for the first attempt and reused by every retry, so a retried session start still reports the customer's metadata instead of an empty object. Metadata set after the snapshot is kept for the next session.
• If playback ends while a start is still in flight, _completeOnConfirm remembers it so the late-confirmed session is completed (sessionComplete) before it is ended, instead of losing the completion.
• The pending-event queue is capped at MAX_EVENT_QUEUE_SIZE = 500 (oldest dropped first), so a start that never resolves cannot grow the queue without bound.

Testing

In adobe-edge: npm test (18 tests, new sessionStart.test.ts covers queue/flush, retry + recovery, rejection, tracker-not-ready race, metadata on retries, late completion, queue cap and orphan close), npm run typescript, npm run build.

Link to Devin session: https://dolby.devinenterprise.com/sessions/37fdbe28150a45588efc33754efcdd32
Requested by: @tvanlaerhoven

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🦋 Changeset detected

Latest commit: 8b556cb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@theoplayer/react-native-analytics-adobe-edge	Patch

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[devin-ai-integration]

Devin Review found 2 new potential issues.