chore(server): 优化环境变量加载与配置

1.  更新.gitignore，忽略所有.env文件但保留.env.example
2.  新增dotenv和cross-env依赖，完善环境变量加载逻辑
3.  新增dev:local本地开发启动脚本，适配多环境配置加载
4.  调整start启动脚本，统一使用cross-env处理环境变量

server/package.json

@@ -5,7 +5,8 @@
 	"private": true,
 	"scripts": {
 		"dev": "midway-bin dev --ts",
-		"start": "NODE_ENV=production midway-bin bootstrap --ts",
+		"dev:local": "cross-env MIDWAY_SERVER_ENV=local midway-bin dev --ts",
+		"start": "cross-env NODE_ENV=production midway-bin bootstrap --ts",
 		"test": "midway-bin test --ts",
 		"lint": "eslint src/**/*.ts",
 		"build": "midway-bin build -c"
@@ -23,6 +24,7 @@
 		"class-transformer": "^0.5.1",
 		"class-validator": "^0.14.1",
 		"dayjs": "^1.11.13",
+		"dotenv": "^17.4.2",
 		"ioredis": "^5.4.1",
 		"jsonwebtoken": "^9.0.2",
 		"pg": "^8.11.0",
@@ -41,6 +43,7 @@
 		"@types/jsonwebtoken": "^9.0.7",
 		"@types/node": "^22.10.0",
 		"@types/uuid": "^10.0.0",
+		"cross-env": "^10.1.0",
 		"jest": "^29.7.0",
 		"ts-jest": "^29.2.5",
 		"typescript": "^5.7.0"