feat: add SQL migration for advanced pricing model

backend/migrations/005_advanced_pricing.sql

@@ -0,0 +1,34 @@
+-- Migration 005: Advanced Pricing (Services and Speed Coefficients)
+
+-- 1. Create services table
+CREATE TABLE IF NOT EXISTS `services` (
+    `id` int(11) NOT NULL AUTO_INCREMENT,
+    `name_en` varchar(255) NOT NULL,
+    `name_ru` varchar(255) DEFAULT NULL,
+    `name_ua` varchar(255) DEFAULT NULL,
+    `desc_en` text DEFAULT NULL,
+    `tech_type` varchar(50) DEFAULT 'fdm',
+    `price_per_hour` decimal(10,2) DEFAULT 0.00,
+    `is_active` tinyint(1) DEFAULT 1,
+    `created_at` timestamp DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+-- 2. Add price_per_hour, speed_coeff and service_id to materials
+-- Using ALTER TABLE with multiple ADD COLUMN for efficiency
+-- Note: IGNORE or existence check is handled by checking if column exists (manually or via script)
+-- But here we just write the ALTER statements.
+
+ALTER TABLE `materials` 
+ADD COLUMN IF NOT EXISTS `price_per_hour` decimal(10,2) DEFAULT NULL,
+ADD COLUMN IF NOT EXISTS `speed_coeff` decimal(10,2) DEFAULT 1.00,
+ADD COLUMN IF NOT EXISTS `service_id` int(11) DEFAULT NULL;
+
+-- 3. Initial seed for services if empty
+INSERT INTO `services` (`name_en`, `name_ru`, `name_ua`, `tech_type`, `price_per_hour`)
+SELECT 'FDM Printing', 'FDM Печать', 'FDM Друк', 'fdm', 2.00
+WHERE NOT EXISTS (SELECT 1 FROM `services` WHERE `tech_type` = 'fdm');
+
+INSERT INTO `services` (`name_en`, `name_ru`, `name_ua`, `tech_type`, `price_per_hour`)
+SELECT 'SLA Printing', 'SLA Печать', 'SLA Друк', 'sla', 5.00
+WHERE NOT EXISTS (SELECT 1 FROM `services` WHERE `tech_type` = 'sla');