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>

CLAUDE.md

@@ -118,8 +118,11 @@ CREATE TABLE qt_configurations (
     name VARCHAR(200) NOT NULL,
     items JSON NOT NULL,                  -- [{"lot_name": "CPU_AMD_9654", "quantity": 2, "unit_price": 11500}]
     total_price DECIMAL(12,2),
+    custom_price DECIMAL(12,2),           -- User-defined target price (for discounts)
     notes TEXT,
     is_template BOOLEAN DEFAULT FALSE,
+    server_count INT DEFAULT 1,           -- Number of servers in configuration
+    price_updated_at TIMESTAMP,           -- Last time prices were refreshed
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     FOREIGN KEY (user_id) REFERENCES qt_users(id)
 );
@@ -268,12 +271,13 @@ POST /api/export/xlsx  → {"items": [...], "name": "Config 1"} → XLSX file
 
 ### Configurations
 ```
-GET    /api/configs           → list user's configurations
-POST   /api/configs           → save new configuration
-GET    /api/configs/:uuid     → get by UUID
-PUT    /api/configs/:uuid     → update
-DELETE /api/configs/:uuid     → delete
-GET    /api/configs/:uuid/export  → export as JSON
+GET    /api/configs                      → list user's configurations
+POST   /api/configs                      → save new configuration
+GET    /api/configs/:uuid                → get by UUID
+PUT    /api/configs/:uuid                → update
+POST   /api/configs/:uuid/refresh-prices → refresh prices for all components
+DELETE /api/configs/:uuid                → delete
+GET    /api/configs/:uuid/export         → export as JSON
 ```
 
 ### Pricing Admin (requires role: pricing_admin or admin)