feat: implement multi-language translation support for products

- Add database migrations for translation tables and digital product fields
- Create MarketplaceProductTranslation model for localized content
- Create ProductTranslation model for vendor translation overrides
- Add product type enum (physical, digital, service, subscription)
- Add digital delivery method and platform fields
- Add numeric price fields (price_numeric, sale_price_numeric)
- Implement language fallback pattern (requested -> 'en' -> None)
- Add helper methods: get_title(), get_description(), get_translation()
- Add vendor override pattern with effective_* properties
- Move title/description from products to translations table

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

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

alembic/versions/f2b3c4d5e6f7_create_translation_tables.py

@@ -0,0 +1,147 @@
+"""Create translation tables for multi-language support
+
+Revision ID: f2b3c4d5e6f7
+Revises: e1a2b3c4d5e6
+Create Date: 2025-12-11
+
+This migration creates:
+- marketplace_product_translations: Localized content from marketplace sources
+- product_translations: Vendor-specific localized overrides
+
+The translation tables support multi-language product information with
+language fallback capabilities. Fields in product_translations can be
+NULL to inherit from marketplace_product_translations.
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "f2b3c4d5e6f7"
+down_revision: Union[str, None] = "e1a2b3c4d5e6"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Create marketplace_product_translations table
+    # Note: Unique constraint is included in create_table for SQLite compatibility
+    op.create_table(
+        "marketplace_product_translations",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "marketplace_product_id",
+            sa.Integer(),
+            sa.ForeignKey("marketplace_products.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("language", sa.String(5), nullable=False),
+        # Localized content
+        sa.Column("title", sa.String(), nullable=False),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column("short_description", sa.String(500), nullable=True),
+        # SEO fields
+        sa.Column("meta_title", sa.String(70), nullable=True),
+        sa.Column("meta_description", sa.String(160), nullable=True),
+        sa.Column("url_slug", sa.String(255), nullable=True),
+        # Source tracking
+        sa.Column("source_import_id", sa.Integer(), nullable=True),
+        sa.Column("source_file", sa.String(), nullable=True),
+        # Timestamps
+        sa.Column(
+            "created_at",
+            sa.DateTime(),
+            nullable=False,
+            server_default=sa.text("CURRENT_TIMESTAMP"),
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(),
+            nullable=False,
+            server_default=sa.text("CURRENT_TIMESTAMP"),
+        ),
+        # Unique constraint included in table creation for SQLite
+        sa.UniqueConstraint(
+            "marketplace_product_id",
+            "language",
+            name="uq_marketplace_product_translation",
+        ),
+    )
+
+    # Create indexes for marketplace_product_translations
+    op.create_index(
+        "idx_mpt_marketplace_product_id",
+        "marketplace_product_translations",
+        ["marketplace_product_id"],
+    )
+    op.create_index(
+        "idx_mpt_language",
+        "marketplace_product_translations",
+        ["language"],
+    )
+
+    # Create product_translations table
+    # Note: Unique constraint is included in create_table for SQLite compatibility
+    op.create_table(
+        "product_translations",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column(
+            "product_id",
+            sa.Integer(),
+            sa.ForeignKey("products.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column("language", sa.String(5), nullable=False),
+        # Overridable localized content (NULL = inherit from marketplace)
+        sa.Column("title", sa.String(), nullable=True),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column("short_description", sa.String(500), nullable=True),
+        # SEO overrides
+        sa.Column("meta_title", sa.String(70), nullable=True),
+        sa.Column("meta_description", sa.String(160), nullable=True),
+        sa.Column("url_slug", sa.String(255), nullable=True),
+        # Timestamps
+        sa.Column(
+            "created_at",
+            sa.DateTime(),
+            nullable=False,
+            server_default=sa.text("CURRENT_TIMESTAMP"),
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(),
+            nullable=False,
+            server_default=sa.text("CURRENT_TIMESTAMP"),
+        ),
+        # Unique constraint included in table creation for SQLite
+        sa.UniqueConstraint("product_id", "language", name="uq_product_translation"),
+    )
+
+    # Create indexes for product_translations
+    op.create_index(
+        "idx_pt_product_id",
+        "product_translations",
+        ["product_id"],
+    )
+    op.create_index(
+        "idx_pt_product_language",
+        "product_translations",
+        ["product_id", "language"],
+    )
+
+
+def downgrade() -> None:
+    # Drop product_translations table and its indexes
+    op.drop_index("idx_pt_product_language", table_name="product_translations")
+    op.drop_index("idx_pt_product_id", table_name="product_translations")
+    op.drop_table("product_translations")
+
+    # Drop marketplace_product_translations table and its indexes
+    op.drop_index("idx_mpt_language", table_name="marketplace_product_translations")
+    op.drop_index(
+        "idx_mpt_marketplace_product_id", table_name="marketplace_product_translations"
+    )
+    op.drop_table("marketplace_product_translations")