Initial commit: Material Texture API service

- Go + Gin + GORM + PostgreSQL backend
- RESTful API for material management
- Docker deployment support
- Database partitioning for billion-scale data
- API documentation

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

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

migrations/003_add_indexes.sql

@@ -0,0 +1,26 @@
+-- ============================================
+-- Migration: 003_add_indexes.sql
+-- Purpose: 添加性能优化索引
+-- ============================================
+
+-- 1. 启用 pg_trgm 扩展 (支持模糊搜索索引)
+CREATE EXTENSION IF NOT EXISTS pg_trgm;
+
+-- 2. 材质名称模糊搜索索引 (GIN 索引，支持 ILIKE '%keyword%')
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_materials_name_trgm
+ON materials USING gin (name gin_trgm_ops);
+
+-- 3. 材质创建时间索引 (用于排序)
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_materials_created_at
+ON materials(created_at DESC);
+
+-- 4. 材质更新时间索引
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_materials_updated_at
+ON materials(updated_at DESC);
+
+-- 注意: 如果使用了分区表 (002_partition_bindings.sql)，
+-- 以下索引已在分区迁移中创建，可跳过
+
+-- 5. binding 表 group_id + material_id 复合索引 (优化批量查询)
+-- CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_bindings_group_material
+-- ON material_bindings(group_id, material_id);