feat(rec): audio analyzer and My Wave v1 engine (M4)

- migration 00006: track features and embeddings (pgvector, HNSW),
  analysis queue filled by a trigger on new tracks, wave sessions and
  impressions, recommender profiles, model versions
- analyzer basic-1 (ADR-014): ffmpeg decode, three 30 s excerpts,
  256-d timbre/rhythm embedding, tempo by onset autocorrelation, key,
  loudness, energy, danceability, acousticness, intro length; worker
  with SKIP LOCKED claims, retries and re-analysis on version change
- wave engine v1: candidates (session/taste similarity, fresh,
  liked artists, rediscover, popular, exploration, seed), filters
  (dislikes, played in 3 h, already served), heuristic score, activity
  and mood fit from contexts.yaml with relaxing thresholds, MMR with
  one track per artist, exploration share, session vector updated by
  reactions and a change of course after three skips
- POST /internal/wave/batch with the catalog index cached in memory
  and the session kept in Redis

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

services/recommender/pipu_rec/wave/contexts.yaml

@@ -0,0 +1,56 @@
+# Занятия и настроения «Моей волны» (docs/recommendations.md#64-занятия-и-настроения).
+# Каждое правило — «колокол» по признаку трека: внутри [min, max] — 1, снаружи спадает по Гауссу с sigma.
+# Признак, которого у трека нет (ещё не проанализирован), не штрафует.
+# Изменения применяются после перезапуска recommender, пересборка образа не нужна (CONTEXTS_PATH).
+activities:
+  running:
+    icon: directions_run
+    rules:
+      - {feature: bpm, min: 150, max: 185, sigma: 12, half_time: true}
+      - {feature: energy, min: 0.7, sigma: 0.12}
+      - {feature: danceability, min: 0.5, sigma: 0.2}
+  workout:
+    icon: fitness_center
+    rules:
+      - {feature: energy, min: 0.75, sigma: 0.1}
+      - {feature: bpm, min: 110, max: 180, sigma: 20, half_time: true}
+  waking_up:
+    icon: wb_sunny
+    rules:
+      - {feature: energy, min: 0.3, max: 0.7, sigma: 0.12}
+      - {feature: valence, min: 0.5, sigma: 0.15}
+  focus:
+    icon: headphones
+    rules:
+      - {feature: energy, min: 0.3, max: 0.6, sigma: 0.12}
+      - {feature: acousticness, min: 0.3, sigma: 0.25}
+  commute:
+    icon: directions_car
+    rules:
+      - {feature: energy, min: 0.4, max: 0.8, sigma: 0.15}
+  chill:
+    icon: weekend
+    rules:
+      - {feature: energy, max: 0.5, sigma: 0.12}
+  sleep:
+    icon: bedtime
+    rules:
+      - {feature: energy, max: 0.35, sigma: 0.1}
+      - {feature: bpm, max: 95, sigma: 12}
+moods:
+  energetic:
+    icon: bolt
+    rules:
+      - {feature: energy, min: 0.7, sigma: 0.12}
+  happy:
+    icon: sentiment_satisfied
+    rules:
+      - {feature: valence, min: 0.6, sigma: 0.12}
+  calm:
+    icon: spa
+    rules:
+      - {feature: energy, max: 0.45, sigma: 0.12}
+  sad:
+    icon: rainy
+    rules:
+      - {feature: valence, max: 0.4, sigma: 0.12}