Add vibe-contextual feedback system with dashboard observability

Adds feedback API endpoints that record up/down/skip signals tied to
vibe context (CLAP embeddings + text). Dashboard now shows Feedback
Activity (recent events with signal counts) and Vibe Influence (how
the same track gets rated differently across vibes).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/haunt_fm/config.py

@@ -23,5 +23,9 @@ class Settings(BaseSettings):
     embedding_batch_size: int = 10
     embedding_interval_seconds: int = 30
 
+    # Feedback
+    feedback_overlap_threshold: float = 0.85
+    feedback_signal_weights: dict = {"up": 1.0, "down": -1.0, "skip": -0.3}
+
 
 settings = Settings()