feat: add optional Laya engine mode for grouping and language detection (#12)

Add a languageDetectionMode setting (algo | laya | laya+algo) exposed
in Settings with three engine choices. When Laya is enabled, a laya
service (Dockerfile.laya, optional compose profile, models stored
outside the repo under ./data/models/laya) can be started, with model
download and deletion from the UI via /laya routes to manage disk
space. Add a channelLanguageFusion service combining Laya results
with the existing algorithm, and wire detection mode through
grouping, channel list and player. Cover engine selection, fusion
and laya service behavior with tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -13,5 +13,20 @@ services:
     environment:
       - NODE_ENV=production
       - PORT=3000 # Internal container port
+      - LAYA_BASE_URL=http://laya:8000
     devices:
       - /dev/dri:/dev/dri # Required for VAAPI/QuickSync/AMF (Linux)
+
+  laya:
+    profiles: ["laya"]
+    build:
+      context: .
+      dockerfile: Dockerfile.laya
+    volumes:
+      - ./data/models/laya:/models
+    environment:
+      - HF_HOME=/models
+      - LAYA_PRELOAD=0
+      - LAYA_HOST=0.0.0.0
+      - LAYA_PORT=8000
+    restart: unless-stopped