feat(backend): Update models and endpoints configuration

- Enhanced ticket and comment models with proper relationships
- Updated client_profile model for better data handling
- Improved auth endpoint with better error handling
- Updated main app configuration and imports
- Added new dependencies to requirements.txt
- Enhanced tickets endpoint with attachment support

backend/app/models/comment.py

@@ -64,6 +64,11 @@ class TicketComment(Base):
     # Relationships
     ticket: Mapped["Ticket"] = relationship("Ticket", back_populates="comments")
     author: Mapped["User"] = relationship("User")
+    attachments: Mapped[list["TicketAttachment"]] = relationship(
+        "TicketAttachment",
+        back_populates="comment",
+        cascade="all, delete-orphan"
+    )
     
     def __repr__(self) -> str:
         return f"<TicketComment {self.id} by {self.author_id}>"