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

web/e2e/specs/export.spec.ts

@@ -867,6 +867,31 @@ test.describe("Multi-Camera Export from History @high", () => {
     await frigateApp.page.route("**/api/recordings/unavailable**", (route) =>
       route.fulfill({ json: [] }),
     );
+    // registered after the broad recordings route so it wins the match;
+    // coverage is an object, and the array above crashes the player
+    await frigateApp.page.route("**/api/*/recordings/coverage**", (route) =>
+      route.fulfill({
+        json: {
+          spans: [
+            {
+              start_time: playbackTime - 3600,
+              end_time: playbackTime + 600,
+              streams: ["main"],
+            },
+          ],
+          codecs_compatible: true,
+          streams: {
+            main: {
+              video_codec: "h264",
+              audio_rate: null,
+              audio_codec: null,
+              has_audio: false,
+              bitrate: 2_000_000,
+            },
+          },
+        },
+      }),
+    );
 
     await frigateApp.goto(`/review?timestamp=front_door_${playbackTime}`);
   }