Migration: Add variant pricing support to database schema

Critical fix for production deployment issue where code changes were
deployed without corresponding database schema updates.

Changes:
- Add Price column to ProductVariants table (decimal 18,2, nullable)
- Add ProductVariantId column to OrderItems table (TEXT, nullable)
- Add index on OrderItems.ProductVariantId for query performance

This migration was manually applied to production on 2025-10-04 to
resolve "no such column: p2.Price" errors that broke the product
catalog API.

Future deployments must include database migration steps in CI/CD.

🤖 Generated with Claude Code
https://claude.com/claude-code

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

LittleShop/Migrations/AddVariantPricing.sql

@@ -0,0 +1,17 @@
+-- Migration: Add Variant Pricing Support
+-- Date: 2025-10-03
+-- Description: Adds Price field to ProductVariants table and ProductVariantId to OrderItems table
+
+-- Add Price column to ProductVariants table
+ALTER TABLE ProductVariants ADD COLUMN Price decimal(18,2) NULL;
+
+-- Add ProductVariantId column to OrderItems table
+ALTER TABLE OrderItems ADD COLUMN ProductVariantId TEXT NULL;
+
+-- Add index on ProductVariantId for performance
+CREATE INDEX IF NOT EXISTS IX_OrderItems_ProductVariantId ON OrderItems (ProductVariantId);
+
+-- Migration complete
+-- No data migration needed - existing records will have NULL values which is correct
+-- Variant Price defaults to NULL (uses product base price)
+-- OrderItems ProductVariantId defaults to NULL (no variant selected)