E2E Test: basic tests.

[cloudwebrtc]

Summary

Adds an end-to-end test (test_connection_basics) to livekit-rtc/tests/test_basic.py. The test exercises the full connect/disconnect/reconnect lifecycle and track publish/subscribe flow across four rtc.Room instances against a live LiveKit server.

What the test covers

Four participants (p1–p4) join a uniquely-named room, then walk through:

1. Visibility — p1 and p2 connect; both reach CONN_CONNECTED.
2. Disconnect propagation — p1 disconnects; p2 receives participant_disconnected for p1.
3. State convergence — p1 then p2 reach CONN_DISCONNECTED.
4. Reconnect cycle — p3 joins → disconnects → reconnects with the same token → disconnects, asserting connection_state after each step.
5. Late joiner sees publishes — p4 joins, p3 reconnects, then publishes a camera track and a mic track. p4 receives track_published for each (the audio future filters by SID so the prior video event doesn't satisfy it) and subscribes to both.
6. Cleanup — p3 and p4 disconnect cleanly.

Requirements

• A reachable LiveKit server (LIVEKIT_URL).
• LIVEKIT_API_KEY / LIVEKIT_API_SECRET for token minting.
• pytest + pytest-asyncio (test is @pytest.mark.asyncio).

Test plan

• Run pytest livekit-rtc/tests/test_basic.py against a local or staging LiveKit deployment with all three env vars set — expect a single passing test.
• Run the same command with the env vars unset — expect a clean skip whose reason names every missing variable.

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

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