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

migrations/036_add_recordings_stream_metadata.py

@@ -0,0 +1,49 @@
+"""Peewee migrations -- 036_add_recordings_stream_metadata.py.
+
+Some examples (model - class or model name)::
+
+    > Model = migrator.orm['model_name']            # Return model in current state by name
+
+    > migrator.sql(sql)                             # Run custom SQL
+    > migrator.python(func, *args, **kwargs)        # Run python code
+    > migrator.create_model(Model)                  # Create a model (could be used as decorator)
+    > migrator.remove_model(model, cascade=True)    # Remove a model
+    > migrator.add_fields(model, **fields)          # Add fields to a model
+    > migrator.change_fields(model, **fields)       # Change fields
+    > migrator.remove_fields(model, *field_names, cascade=True)
+    > migrator.rename_field(model, old_field_name, new_field_name)
+    > migrator.rename_table(model, new_table_name)
+    > migrator.add_index(model, *col_names, unique=False)
+    > migrator.drop_index(model, *col_names)
+    > migrator.add_not_null(model, *field_names)
+    > migrator.drop_not_null(model, *field_names)
+    > migrator.add_default(model, field_name, default)
+
+"""
+
+import peewee as pw
+
+SQL = pw.SQL
+
+
+def migrate(migrator, database, fake=False, **kwargs):
+    migrator.sql(
+        'ALTER TABLE "recordings" ADD COLUMN "stream_type" VARCHAR(8) NOT NULL DEFAULT \'main\''
+    )
+    migrator.sql(
+        'CREATE INDEX IF NOT EXISTS "recordings_camera_stream_type" ON "recordings" ("camera", "stream_type")'
+    )
+
+    # nullable so legacy rows stay NULL, meaning unknown
+    migrator.sql('ALTER TABLE "recordings" ADD COLUMN "has_audio" INTEGER')
+    migrator.sql('ALTER TABLE "recordings" ADD COLUMN "audio_rate" INTEGER')
+    migrator.sql('ALTER TABLE "recordings" ADD COLUMN "audio_codec" TEXT')
+    migrator.sql('ALTER TABLE "recordings" ADD COLUMN "video_codec" TEXT')
+
+    # keyframe offsets in ms from segment start; nullable so legacy rows
+    # stay NULL and playback serves whole files for them
+    migrator.sql('ALTER TABLE "recordings" ADD COLUMN "keyframes" TEXT')
+
+
+def rollback(migrator, database, fake=False, **kwargs):
+    pass