Add sub stream recording with adaptive quality playback (#24009)

* add sub stream recording with adaptive quality playback

Optionally record a second, lower bitrate stream alongside the main
recording stream via a `record_sub` input role and `record.sub` config block, with its own retention windows.
Recordings rows now carry the stream type plus the media details needed to serve both streams from one manifest: video codec, audio presence, audio codec and rate, and a record-time keyframe index.

Playback resolves coverage across both streams and merges them into a single VOD sequence, falling back to a discontinuity manifest with per-clip init segments when the media signatures differ. The player exposes a quality selector, and an auto governor picks the stream from stall time, bandwidth, codec support, and the save-data hint.

* fix tests and i18n

frigate/util/classification.py

@@ -18,6 +18,7 @@ from frigate.const import (
     CLIPS_DIR,
     MODEL_CACHE_DIR,
     PROCESS_PRIORITY_LOW,
+    STREAM_TYPE_MAIN,
     UPDATE_MODEL_STATE,
 )
 from frigate.log import redirect_output_to_logger, suppress_stderr_during
@@ -555,6 +556,7 @@ def _extract_keyframes(
                     (timestamp >= Recordings.start_time)
                     & (timestamp <= Recordings.end_time)
                     & (Recordings.camera == camera)
+                    & (Recordings.stream_type == STREAM_TYPE_MAIN)
                 )
                 .order_by(Recordings.start_time.desc())
                 .limit(1)