Add reference data models and seed data for incoterms, invoice types, material types, payment methods, pedimento codes, pedimento regimens, sectors, states, transport modes, transport types, and valuation methods

- Implemented SQLAlchemy models for incoterms, invoice types, material types, payment methods, pedimento codes, pedimento regimens, sectors, states, transport modes, transport types, and valuation methods.
- Added seed data for each reference data model to populate the database with initial values.
- Ensured primary key constraints and appropriate data types for each model.
- Established relationships where necessary, particularly in pedimento codes and regimens.

backend/api/v1/modules/public/reference_data/containers/models.py

@@ -0,0 +1,16 @@
+from sqlalchemy import String, PrimaryKeyConstraint
+from sqlalchemy.orm import mapped_column, Mapped
+from core.database import Base
+
+class Container(Base):
+    __tablename__ = "containers" #GContenedores
+    __table_args__ = (
+        PrimaryKeyConstraint("key", name="containers_pkey"),
+        {"schema": "public"}  # opcional
+    )
+
+    key: Mapped[str] = mapped_column(String(3), nullable=False)  # mantiene ceros iniciales
+    description: Mapped[str] = mapped_column(String(500), nullable=False)  # descripción legal en español
+
+    def __repr__(self):
+        return f"<Container(key={self.key}, description={self.description})>"