feat(admin): wave metrics split by model version (M6)

The library page compares listen-through, early-skip and like rates per
impression model version, so v1 and the trained ranker can be compared online.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/openapi.yaml

@@ -3096,7 +3096,7 @@ components:
           nullable: true
     WaveMetrics:
       type: object
-      required: [served, listen_through_rate, early_skip_rate, like_rate, sessions]
+      required: [served, listen_through_rate, early_skip_rate, like_rate, sessions, by_model]
       description: Метрики волны за 7 дней
       properties:
         served:
@@ -3113,6 +3113,28 @@ components:
           description: Лайков на 100 треков
         sessions:
           type: integer
+        by_model:
+          type: array
+          description: Те же метрики по версии модели показа (v1 / ALS / ранжировщик) — сравнение онлайн
+          items:
+            $ref: '#/components/schemas/WaveModelMetrics'
+    WaveModelMetrics:
+      type: object
+      required: [model_ver, served, listen_through_rate, early_skip_rate, like_rate]
+      properties:
+        model_ver:
+          type: string
+        served:
+          type: integer
+        listen_through_rate:
+          type: number
+          nullable: true
+        early_skip_rate:
+          type: number
+          nullable: true
+        like_rate:
+          type: number
+          nullable: true
     AndroidRelease:
       type: object
       required: [version, version_code, notes_md, size, sha256, download_url, min_supported]