chore: streamline workspace make workflows

Clarify product-level server and desktop commands while moving backend-only maintenance tasks into backend/Makefile. This keeps root automation focused on core flows and aligns the main OpenSpec specs with the new command boundaries.

backend/README.md

@@ -437,24 +437,37 @@ docker run -d -e NEX_SERVER_PORT=9000 -e NEX_LOG_LEVEL=info nex-server
 ## 测试
 
 ```bash
-# 运行所有测试
+# 运行 backend 默认测试
 make test
 
+# 分类测试
+make test-unit
+make test-integration
+
 # 生成覆盖率报告
 make test-coverage
+
+# MySQL 专项测试
+make mysql-up
+make mysql-down
+make mysql-test
+make mysql-test-quick
 ```
 
 ## 数据库迁移
 
 ```bash
 # 使用 Makefile
-make migrate-up DB_PATH=~/.nex/config.db
-make migrate-down DB_PATH=~/.nex/config.db
-make migrate-status DB_PATH=~/.nex/config.db
+make migrate-up DB_DSN=~/.nex/config.db
+make migrate-down DB_DSN=~/.nex/config.db
+make migrate-status DB_DSN=~/.nex/config.db
 
 # 创建新迁移
 make migrate-create
 
+# MySQL 迁移
+make migrate-up DB_DRIVER=mysql DB_DSN='user:pass@tcp(localhost:3306)/nex'
+
 # 或直接使用 goose
 goose -dir migrations sqlite3 ~/.nex/config.db up
 ```
@@ -571,9 +584,12 @@ GET  /anthropic/v1/models
 ## 开发
 
 ```bash
-make build    # 构建
-make lint     # 代码检查
-make deps     # 整理依赖
+make build           # 构建 backend/bin/server
+make run             # 运行后端服务
+make lint            # 代码检查
+make clean           # 清理 backend 构建产物
+go mod tidy          # 整理依赖
+go generate ./...    # 刷新 mock 等生成代码
 ```
 
 环境要求：Go 1.26 或更高版本