Initial MVP: full-stack music discovery app

Backend (FastAPI):
- User auth with email/password and Spotify OAuth
- Spotify playlist import with audio feature extraction
- AI recommendation engine using Claude API with taste profiling
- Save/bookmark recommendations
- Rate limiting for free tier (10 recs/day, 1 playlist)
- PostgreSQL models with Alembic migrations
- Redis-ready configuration

Frontend (React 19 + TypeScript + Vite + Tailwind):
- Landing page, auth flows (email + Spotify OAuth)
- Dashboard with stats and quick discover
- Playlist management and import from Spotify
- Discover page with custom query support
- Recommendation cards with explanations and save toggle
- Taste profile visualization
- Responsive layout with mobile navigation
- PWA-ready configuration

Infrastructure:
- Docker Compose with PostgreSQL, Redis, backend, frontend
- Environment-based configuration

backend/app/models/playlist.py

@@ -0,0 +1,28 @@
+from datetime import datetime, timezone
+
+from sqlalchemy import String, Integer, DateTime, ForeignKey, JSON, Text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+
+class Playlist(Base):
+    __tablename__ = "playlists"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), index=True)
+    name: Mapped[str] = mapped_column(String(500))
+    platform_source: Mapped[str] = mapped_column(String(50))  # spotify, manual, etc.
+    external_id: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    track_count: Mapped[int] = mapped_column(Integer, default=0)
+    taste_profile: Mapped[dict | None] = mapped_column(JSON, nullable=True)
+    imported_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
+    )
+
+    user: Mapped["User"] = relationship(back_populates="playlists")
+    tracks: Mapped[list["Track"]] = relationship(back_populates="playlist", cascade="all, delete-orphan")
+
+
+from app.models.user import User  # noqa: E402, F811
+from app.models.track import Track  # noqa: E402