feat(web): My Wave button, mood picker and endless wave playback (M4)

- WaveButton: TypeScript port of the prototype's canvas animation
  (orb and liquid), breathing at rest, pulsing to the track's BPM and
  energy in the cover palette, following the cursor, pressing with a
  spring; reduced motion and hidden tabs slow or stop it
- home: the wave in the centre with activity and mood chips; changing
  them while playing rebuilds the upcoming tracks without stopping
- player wave mode: asks for the next batch when two tracks are left,
  sends complete / skip / early skip / like / dislike as feedback and
  refreshes the queue right after a reaction or an early skip
- tracks expose bpm, energy and loudness once analysed; library page
  shows analysis progress and 7-day wave metrics; wave style setting

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

api/openapi.yaml

@@ -1763,7 +1763,7 @@ components:
             type: string
     Track:
       type: object
-      required: [id, title, duration_ms, artists, album, genres, disc_no, track_no, available, stream_url, reaction]
+      required: [id, title, duration_ms, artists, album, genres, disc_no, track_no, available, stream_url, reaction, features]
       properties:
         id:
           type: string
@@ -1799,6 +1799,11 @@ components:
           nullable: true
           allOf:
             - $ref: "#/components/schemas/Reaction"
+        features:
+          nullable: true
+          description: Аудиопризнаки (после анализа) — для анимации волны и выравнивания громкости
+          allOf:
+            - $ref: "#/components/schemas/TrackFeatures"
     Artist:
       type: object
       required: [id, name, album_count, track_count]
@@ -1904,6 +1909,19 @@ components:
         next_cursor:
           type: string
           nullable: true
+    TrackFeatures:
+      type: object
+      required: [bpm, energy, loudness_lufs]
+      properties:
+        bpm:
+          type: number
+          nullable: true
+        energy:
+          type: number
+          nullable: true
+        loudness_lufs:
+          type: number
+          nullable: true
     StreamQuality:
       type: string
       enum: [auto, original, high, medium, low]