* test(collab): add deterministic browser sessions
- Extract a typed room transport boundary around Trystero
- Add a development-only WebSocket relay transport for browser tests
- Cover two-peer edits, awareness, departure cleanup, and reconnect convergence without public network services
* fix(collab): harden browser test transport
- Scope collaboration controls to explicit development test hooks
- Validate bounded relay messages and reject duplicate action receivers
- Remove only awareness clients owned by a departing peer
- Guarantee relay and browser cleanup after setup failures
* fix(collab): strengthen browser session coverage
- Prevent remote awareness rebroadcast and track ownership by transport peer
- Guard and validate the development relay lifecycle
- Simulate a network partition with retained peers and concurrent offline edits
- Make browser and relay setup and teardown failure-safe
* test(collab): prove partitioned peer convergence
- Queue and assert traffic during a deterministic network partition
- Converge non-conflicting edits from retained host and guest sessions
- Reject relay startup failures and guard test-only browser APIs
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