feat(config): add recommendation section (weighted shuffle weights)

BaseWeight, LikeBoost, RecencyWeight, SkipPenalty, JitterMagnitude,
RecentlyPlayedHours, RadioSize, RadioSizeMax. Defaults match spec §6.

config.example.yaml

@@ -45,3 +45,21 @@ events:
   # this threshold AND duration played (ms) is below the next threshold.
   skip_max_completion_ratio: 0.5
   skip_max_duration_played_ms: 30000
+
+recommendation:
+  # Base score every candidate gets before adjustments. Spec §6.
+  base_weight: 1.0
+  # Bonus for tracks the user has liked (general_likes).
+  like_boost: 2.0
+  # Multiplier on recency_decay (1.0 for tracks ≥ 30 days stale, 0 for fresh).
+  recency_weight: 1.0
+  # Penalty multiplier on skip_ratio (skips/plays); 1.0 = full penalty.
+  skip_penalty: 1.0
+  # ± random jitter applied to every candidate; breaks ties without dominating.
+  jitter_magnitude: 0.1
+  # Hard-suppression window: tracks played within this many hours never appear.
+  recently_played_hours: 1
+  # Default radio size when ?limit= is not specified.
+  radio_size: 50
+  # Maximum allowed ?limit= (server caps to this regardless).
+  radio_size_max: 200