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/001_init.sql

@@ -0,0 +1,37 @@
+-- 材质管理系统初始化脚本
+-- 此脚本由GORM AutoMigrate自动执行，仅作参考
+
+-- 材质表
+CREATE TABLE IF NOT EXISTS materials (
+    id          BIGSERIAL PRIMARY KEY,
+    name        VARCHAR(255) NOT NULL,
+    diffuse_r   FLOAT NOT NULL DEFAULT 0,
+    diffuse_g   FLOAT NOT NULL DEFAULT 0,
+    diffuse_b   FLOAT NOT NULL DEFAULT 0,
+    alpha       FLOAT NOT NULL DEFAULT 1,
+    shininess   FLOAT NOT NULL DEFAULT 0,
+    specular_r  FLOAT NOT NULL DEFAULT 0,
+    specular_g  FLOAT NOT NULL DEFAULT 0,
+    specular_b  FLOAT NOT NULL DEFAULT 0,
+    ambient_r   FLOAT NOT NULL DEFAULT 0,
+    ambient_g   FLOAT NOT NULL DEFAULT 0,
+    ambient_b   FLOAT NOT NULL DEFAULT 0,
+    metallic    FLOAT NOT NULL DEFAULT 0,
+    roughness   FLOAT NOT NULL DEFAULT 0.5,
+    reflectance FLOAT NOT NULL DEFAULT 0.5,
+    created_at  TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    updated_at  TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+
+-- 材质绑定表
+CREATE TABLE IF NOT EXISTS material_bindings (
+    id          BIGSERIAL PRIMARY KEY,
+    material_id BIGINT NOT NULL REFERENCES materials(id) ON DELETE CASCADE,
+    group_id    VARCHAR(255) NOT NULL,
+    created_at  TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+
+-- 索引
+CREATE INDEX IF NOT EXISTS idx_bindings_material_id ON material_bindings(material_id);
+CREATE INDEX IF NOT EXISTS idx_bindings_group_id ON material_bindings(group_id);
+CREATE UNIQUE INDEX IF NOT EXISTS idx_unique_material_group ON material_bindings(material_id, group_id);