Add price refresh functionality to configurator

- Add price_updated_at field to qt_configurations table to track when prices were last updated
- Add RefreshPrices() method in configuration service to update all component prices with current values from database
- Add POST /api/configs/:uuid/refresh-prices API endpoint for price updates
- Add "Refresh Prices" button in configurator UI next to Save button
- Display last price update timestamp in human-readable format (e.g., "5 min ago", "2 hours ago")
- Create migration 004_add_price_updated_at.sql for database schema update
- Update CLAUDE.md documentation with new API endpoint and schema changes
- Add MIGRATION_PRICE_REFRESH.md with detailed migration instructions

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

migrations/004_add_price_updated_at.sql

@@ -0,0 +1,4 @@
+-- Add price_updated_at column to qt_configurations table
+ALTER TABLE qt_configurations
+ADD COLUMN price_updated_at TIMESTAMP NULL DEFAULT NULL
+AFTER server_count;