🐛 fix(mysql): 修复旧版 Windows 无法解析 Asia/Shanghai 时区

- 嵌入 Go IANA 时区数据，兼容 Windows Server 2012 等缺少 zoneinfo 的环境
- 保持 MySQL serverTimezone=GMT+8 到 loc=Asia/Shanghai 的时间语义
- 增加 MySQL DSN 时区解析回归测试
Refs #449

internal/db/mysql_connection_params_test.go

@@ -1,6 +1,7 @@
 package db
 
 import (
+	"database/sql"
 	"net/url"
 	"strings"
 	"testing"
@@ -121,6 +122,28 @@ func TestMySQLDSN_MapsJDBCUTF8EncodingToMySQLCharset(t *testing.T) {
 	}
 }
 
+func TestMySQLDSN_AsiaShanghaiLocationAcceptedByDriver(t *testing.T) {
+	t.Parallel()
+
+	m := &MySQLDB{}
+	dsn, err := m.getDSN(connection.ConnectionConfig{
+		Host:             "127.0.0.1",
+		Port:             3306,
+		User:             "root",
+		Database:         "app",
+		ConnectionParams: "serverTimezone=GMT%2B8",
+	})
+	if err != nil {
+		t.Fatalf("getDSN failed: %v", err)
+	}
+
+	db, err := sql.Open("mysql", dsn)
+	if err != nil {
+		t.Fatalf("mysql driver should accept loc=Asia/Shanghai: %v", err)
+	}
+	_ = db.Close()
+}
+
 func TestMySQLDSN_URIParamsAndExplicitParamsPrecedence(t *testing.T) {
 	t.Parallel()
 

internal/db/timezone_data.go

@@ -0,0 +1,6 @@
+package db
+
+// Embed the IANA time zone database so Windows deployments without zoneinfo
+// files, such as Windows Server 2012, can still resolve locations like
+// Asia/Shanghai when database drivers parse DSN time zone parameters.
+import _ "time/tzdata"