Send all batchable commands in sdp offer

[roznawsk]

Description

This allows for negotiating both audio and video at the same time.

Motivation and Context

Why is this change required? What problem does it solve? If it fixes an open
issue, please link to the issue here.

Documentation impact

• Documentation update required
• Documentation updated in another PR
• No documentation update required

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)

[linear]

FCE-1232

[Copilot]

Pull request overview

This PR updates the WebRTC client’s command queue/renegotiation flow so multiple locally queued addTrack operations can be included in a single SDP offer/answer cycle (i.e., batchable commands are drained right before creating the offer).

Changes:

• Mark addTrack commands as batchable and drain batchable commands in onOfferData before creating/sending the SDP offer.
• Avoid sending redundant renegotiateTracks when an addTrack happens while a renegotiation is already pending.
• Add vitest coverage for batching behavior and extend test fixtures/mocks to support the new flow.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/webrtc-client/src/CommandsQueue.ts	Adds batching support and multi-notifier tracking for queued commands.
packages/webrtc-client/src/webRTCEndpoint.ts	Drains batchable commands before generating an SDP offer.
packages/webrtc-client/src/tracks/LocalTrackManager.ts	Skips redundant renegotiateTracks while renegotiation is already pending.
packages/webrtc-client/tests/methods/addTrackBatching.test.ts	New tests covering batching and error isolation within a batched cycle.
packages/webrtc-client/tests/fixtures.ts	Adds helper to build multi-track SDP answers for tests.
packages/webrtc-client/tests/mocks.ts	Adjusts RTCPeerConnection mock signaling state for instability checks.

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 13 changed files in this pull request and generated 2 comments.