feat: SuperAdmin bootstrap, i18n sync fix and AssetAssignment ORM fix

- Fixed AttributeError in User model (added region_code, preferred_language)
- Fixed InvalidRequestError in AssetAssignment (added organization relationship)
- Configured STATIC_DIR for translation sync
- Applied Alembic migrations for user schema updates

backend/app/models/asset.py

@@ -75,7 +75,9 @@ class AssetReview(Base):
     criteria_scores = Column(JSON, server_default=text("'{}'::jsonb")) 
     comment = Column(Text)
     created_at = Column(DateTime(timezone=True), server_default=func.now())
+    
     asset = relationship("Asset", back_populates="reviews")
+    user = relationship("User") # <--- JAVÍTÁS: Hozzáadva
 
 class AssetAssignment(Base):
     __tablename__ = "asset_assignments"
@@ -86,7 +88,9 @@ class AssetAssignment(Base):
     assigned_at = Column(DateTime(timezone=True), server_default=func.now())
     released_at = Column(DateTime(timezone=True), nullable=True)
     status = Column(String(30), default="active")
+    
     asset = relationship("Asset", back_populates="assignments")
+    organization = relationship("Organization") # <--- KRITIKUS JAVÍTÁS: Ez okozta a login hibát
 
 class AssetEvent(Base):
     __tablename__ = "asset_events"
@@ -115,7 +119,10 @@ class AssetCost(Base):
     date = Column(DateTime(timezone=True), server_default=func.now())
     mileage_at_cost = Column(Integer)
     data = Column(JSON, server_default=text("'{}'::jsonb"))
+    
     asset = relationship("Asset", back_populates="costs")
+    organization = relationship("Organization") # <--- JAVÍTÁS: Hozzáadva
+    driver = relationship("User") # <--- JAVÍTÁS: Hozzáadva
 
 class ExchangeRate(Base):
     __tablename__ = "exchange_rates"