refactor(server): 优化服务器启动脚本和数据库连接逻辑

修改run_server.sh脚本以支持环境变量和构建选项
移除mysql.go中无效的默认连接字符串并修复代码格式

scripts/run_server.sh

@@ -1,5 +1,17 @@
 #!/usr/bin/env bash
 set -e
 cd "$(dirname "$0")/.."/server
+set -a
+[ -f .env.local ] && source .env.local
+set +a
+if [ "${SKIP_YMT:-0}" = "1" ]; then
+  unset YMT_DB_USER YMT_DB_PASSWORD YMT_DB_HOST YMT_DB_PORT YMT_DB_NAME
+fi
 go mod tidy
-go run ./cmd/server
+if [ "${BUILD:-0}" = "1" ]; then
+  mkdir -p bin
+  go build -o bin/marketing-data-server ./cmd/server
+  PORT=${PORT:-8077} ./bin/marketing-data-server
+else
+  go run ./cmd/server
+fi

server/internal/db/mysql.go

@@ -2,13 +2,11 @@ package db
 
 import (
 	"database/sql"
+
 	_ "github.com/go-sql-driver/mysql"
 )
 
 func ConnectMySQL(dsn string) (*sql.DB, error) {
-    if dsn == "" {
-        return sql.Open("mysql", "invalid:invalid@tcp(localhost:3306)/invalid")
-    }
 	db, err := sql.Open("mysql", dsn)
 	if err != nil {
 		return nil, err