🎉 Initial commit: AudiOhm - Alternative à Spotify avec streaming YouTube

Features:
- Frontend Flutter avec thème néon cyberpunk
- Backend FastAPI avec streaming YouTube
- Base de données PostgreSQL + Redis
- Authentification JWT complète
- Recherche multi-source (DB + YouTube)
- Playlists CRUD avec drag & drop
- Queue management
- Settings avec audio quality
- Interface adaptative (Desktop + Mobile)

Tech Stack:
- Frontend: Flutter 3.2+, Riverpod
- Backend: Python 3.11+, FastAPI
- Database: PostgreSQL 15+
- Cache: Redis 7+
- Streaming: yt-dlp + FFmpeg

🚀 Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/models/playlist_track.py

@@ -0,0 +1,96 @@
+"""Playlist-Track association model."""
+import uuid
+from datetime import datetime
+from typing import TYPE_CHECKING
+
+from sqlalchemy import Integer, ForeignKey, UniqueConstraint
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.core.database import Base
+
+if TYPE_CHECKING:
+    from app.models.playlist import Playlist
+    from app.models.track import Track
+    from app.models.user import User
+
+
+class PlaylistTrack(Base):
+    """Association model for Playlist-Track many-to-many relationship."""
+
+    __tablename__ = "playlist_tracks"
+    __table_args__ = (
+        UniqueConstraint("playlist_id", "position", name="uq_playlist_position"),
+    )
+
+    # Primary key
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        primary_key=True,
+        default=uuid.uuid4,
+        index=True,
+    )
+
+    # Foreign keys
+    playlist_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("playlists.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    track_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("tracks.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+
+    # Position in playlist (starts at 0)
+    position: Mapped[int] = mapped_column(
+        Integer,
+        nullable=False,
+    )
+
+    # User who added this track to playlist
+    added_by: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("users.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+
+    # Timestamp when track was added
+    added_at: Mapped[datetime] = mapped_column(
+        default=datetime.utcnow,
+        nullable=False,
+    )
+
+    # Relationships
+    playlist: Mapped["Playlist"] = relationship(
+        "Playlist",
+        back_populates="playlist_tracks",
+        lazy="selectin",
+    )
+    track: Mapped["Track"] = relationship(
+        "Track",
+        lazy="selectin",
+    )
+    added_by_user: Mapped["User"] = relationship(
+        "User",
+        back_populates="added_playlist_tracks",
+        lazy="selectin",
+        foreign_keys=[added_by],
+    )
+
+    def __repr__(self) -> str:
+        return f"<PlaylistTrack playlist={self.playlist_id} track={self.track_id} pos={self.position}>"
+
+    def to_dict(self) -> dict:
+        """Convert playlist-track model to dictionary."""
+        return {
+            "id": str(self.id),
+            "playlist_id": str(self.playlist_id),
+            "track_id": str(self.track_id),
+            "position": self.position,
+            "added_by": str(self.added_by) if self.added_by else None,
+            "added_at": self.added_at.isoformat(),
+        }