Initial haunt-fm implementation

Full music recommendation pipeline: listening history capture via webhook,
Last.fm candidate discovery, iTunes preview download, CLAP audio embeddings
(512-dim), pgvector cosine similarity recommendations, playlist generation
with known/new track interleaving, and Music Assistant playback via HA.

Includes: FastAPI app, SQLAlchemy models, Alembic migrations, Docker Compose
with pgvector/pg17, status dashboard, and all API endpoints.

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

src/haunt_fm/api/playlists.py

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+from fastapi import APIRouter, Depends
+from pydantic import BaseModel
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from haunt_fm.db import get_session
+from haunt_fm.models.track import PlaylistTrack, Track
+from haunt_fm.services.music_assistant import play_playlist_on_speaker
+from haunt_fm.services.playlist_generator import generate_playlist
+
+router = APIRouter(prefix="/api/playlists")
+
+
+class GenerateRequest(BaseModel):
+    total_tracks: int = 20
+    known_pct: int = 30
+    name: str | None = None
+    speaker_entity: str | None = None
+    auto_play: bool = False
+
+
+@router.post("/generate")
+async def generate(req: GenerateRequest, session: AsyncSession = Depends(get_session)):
+    playlist = await generate_playlist(
+        session,
+        total_tracks=req.total_tracks,
+        known_pct=req.known_pct,
+        name=req.name,
+    )
+
+    # Load playlist tracks with track info
+    result = await session.execute(
+        select(PlaylistTrack, Track)
+        .join(Track, PlaylistTrack.track_id == Track.id)
+        .where(PlaylistTrack.playlist_id == playlist.id)
+        .order_by(PlaylistTrack.position)
+    )
+    rows = result.all()
+
+    track_list = [
+        {
+            "position": pt.position,
+            "artist": t.artist,
+            "title": t.title,
+            "album": t.album,
+            "is_known": pt.is_known,
+            "similarity_score": pt.similarity_score,
+        }
+        for pt, t in rows
+    ]
+
+    # Auto-play if requested
+    if req.auto_play and req.speaker_entity:
+        await play_playlist_on_speaker(track_list, req.speaker_entity)
+
+    return {
+        "playlist_id": playlist.id,
+        "name": playlist.name,
+        "total_tracks": playlist.total_tracks,
+        "known_pct": playlist.known_pct,
+        "tracks": track_list,
+        "auto_played": req.auto_play and req.speaker_entity is not None,
+    }