Integrate WeChat Official Account support and update configuration

- Added WeChat Official Account configuration options to .env.example and config.go for OAuth2 integration.
- Updated main.go to initialize WeChat OAuth handler and register routes for handling OAuth requests.
- Enhanced documentation to include references for WeChat Official Account functionality.
- Updated route registration to accommodate the new OAuth handler for improved API structure.

config/config.go

@@ -15,6 +15,7 @@ type Config struct {
 	JWT        JWTConfig
 	ShortVideo ShortVideoConfig
 	Qiniu      QiniuConfig
+	WeChatOA   WeChatOfficialConfig
 }
 
 type ServerConfig struct {
@@ -53,6 +54,13 @@ type QiniuConfig struct {
 	TokenExpireSeconds int
 }
 
+// WeChatOfficialConfig 用于微信公众号网页授权（OAuth2）相关接口。
+type WeChatOfficialConfig struct {
+	AppID          string
+	AppSecret      string
+	RequestTimeout time.Duration
+}
+
 var AppConfig *Config
 
 func LoadConfig() {
@@ -91,6 +99,11 @@ func LoadConfig() {
 			KeyPrefix:          getEnv("QINIU_KEY_PREFIX", "uploads/"),
 			TokenExpireSeconds: getEnvAsInt("QINIU_TOKEN_EXPIRE_SECONDS", 300),
 		},
+		WeChatOA: WeChatOfficialConfig{
+			AppID:          getEnv("WECHAT_OA_APP_ID", ""),
+			AppSecret:      getEnv("WECHAT_OA_APP_SECRET", ""),
+			RequestTimeout: time.Duration(getEnvAsInt("WECHAT_OA_TIMEOUT_SECONDS", 5)) * time.Second,
+		},
 	}
 }