[swayamg20]

Summary

#564 added event-type filtering, which fixed the leak in the title, but every AudioStream and VideoStream subscriber still received every other stream's frame events, so the event-loop work grew with the square of the stream count. AudioSource.capture_frame also subscribed to all FFI events on every frame.

• AudioStream and VideoStream filters also match stream_handle against the stream's own handle once the create request returns. They still subscribe before creating the stream, so no early frames or EOS are missed
• capture_frame subscribes only to capture_audio_frame events, narrowed to its own async_id once the request returns

This uses the same handle filter as data_track.py and data_stream.py, and doesn't touch FfiQueue, so it's independent of #892.

Refs #563

Testing

• uv run pytest tests/rtc/test_media_ffi_filter.py tests/rtc/test_ffi_queue.py tests/rtc/test_room_ffi_filter.py -q -W error
• uv run mypy livekit-rtc
• uv run ruff check . and uv run ruff format --check .

[devin-ai-integration]

✅ Devin Review: No Issues Found

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

[cloudwebrtc]

lgtm!