prod: UI Optimisée mise en production

- Documentation archivée et réorganisée
- Backend: Ajout tests, migrations, library service, rate limiting
- Frontend: Suppression Flutter, focus sur interface web HTML/JS
- Tailwind CSS ajouté pour le style
- Améliorations UX et corrections bugs

Generated with [Claude Code](https://claude.com/claude-code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

backend/app/models/user.py

@@ -12,6 +12,8 @@ from app.core.database import Base
 if TYPE_CHECKING:
     from app.models.playlist import Playlist
     from app.models.playlist_track import PlaylistTrack
+    from app.models.listening_history import ListeningHistory
+    from app.models.liked_track import LikedTrack
 
 
 class User(Base):
@@ -100,6 +102,20 @@ class User(Base):
         lazy="selectin",
     )
 
+    listening_history: Mapped[list["ListeningHistory"]] = relationship(
+        "ListeningHistory",
+        back_populates="user",
+        cascade="all, delete-orphan",
+        lazy="selectin",
+    )
+
+    liked_tracks: Mapped[list["LikedTrack"]] = relationship(
+        "LikedTrack",
+        back_populates="user",
+        cascade="all, delete-orphan",
+        lazy="selectin",
+    )
+
     def __repr__(self) -> str:
         return f"<User {self.username} ({self.email})>"