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/ticket.py

@@ -126,6 +126,12 @@ class Ticket(Base):
         cascade="all, delete-orphan"
     )
     
+    attachments: Mapped[list["TicketAttachment"]] = relationship(
+        "TicketAttachment",
+        back_populates="ticket",
+        cascade="all, delete-orphan"
+    )
+    
     # ✅ AÑADIDOS: Constraints según schema.sql
     __table_args__ = (
         UniqueConstraint('tenant_id', 'ticket_number', name='uq_tickets_tenant_number'),