feat: enhance Letzshop order import with EAN matching and stats

- Add historical order import with pagination support
- Add customer_locale, shipping_country_iso, billing_country_iso columns
- Add gtin/gtin_type columns to Product table for EAN matching
- Fix order stats to count all orders server-side (not just visible page)
- Add GraphQL introspection script with tracking workaround tests
- Enrich inventory units with EAN, MPN, SKU, product name
- Add LetzshopOrderStats schema for proper status counts

Migrations:
- a9a86cef6cca: Add locale and country fields to letzshop_orders
- cb88bc9b5f86: Add gtin columns to products table

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

alembic/versions/a9a86cef6cca_add_letzshop_order_locale_and_country_.py

@@ -0,0 +1,31 @@
+"""add_letzshop_order_locale_and_country_fields
+
+Revision ID: a9a86cef6cca
+Revises: fcfdc02d5138
+Create Date: 2025-12-17 20:55:41.477848
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'a9a86cef6cca'
+down_revision: Union[str, None] = 'fcfdc02d5138'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Add new columns to letzshop_orders for customer locale and country
+    op.add_column('letzshop_orders', sa.Column('customer_locale', sa.String(length=10), nullable=True))
+    op.add_column('letzshop_orders', sa.Column('shipping_country_iso', sa.String(length=5), nullable=True))
+    op.add_column('letzshop_orders', sa.Column('billing_country_iso', sa.String(length=5), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column('letzshop_orders', 'billing_country_iso')
+    op.drop_column('letzshop_orders', 'shipping_country_iso')
+    op.drop_column('letzshop_orders', 'customer_locale')

alembic/versions/cb88bc9b5f86_add_gtin_columns_to_product_table.py

@@ -0,0 +1,37 @@
+"""add_gtin_columns_to_product_table
+
+Revision ID: cb88bc9b5f86
+Revises: a9a86cef6cca
+Create Date: 2025-12-18 20:54:55.185857
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'cb88bc9b5f86'
+down_revision: Union[str, None] = 'a9a86cef6cca'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Add GTIN (EAN/UPC barcode) columns to products table for order EAN matching
+    # gtin: The barcode number (e.g., "0889698273022")
+    # gtin_type: The format type from Letzshop (e.g., "gtin13", "gtin14", "isbn13")
+    op.add_column('products', sa.Column('gtin', sa.String(length=50), nullable=True))
+    op.add_column('products', sa.Column('gtin_type', sa.String(length=20), nullable=True))
+
+    # Add index for EAN lookups during order matching
+    op.create_index('idx_product_gtin', 'products', ['gtin'], unique=False)
+    op.create_index('idx_product_vendor_gtin', 'products', ['vendor_id', 'gtin'], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index('idx_product_vendor_gtin', table_name='products')
+    op.drop_index('idx_product_gtin', table_name='products')
+    op.drop_column('products', 'gtin_type')
+    op.drop_column('products', 'gtin')