feat(equalize): Enhance EqualizeConfig to support external API URL

- Added ExternalAPIURL to EqualizeConfig for public EQ interface usage.
- Updated loadEqualize function to initialize ExternalAPIURL from environment variable or default value.
- Refactored reqEqualize method to accept apiURL as a parameter for improved flexibility.
- Introduced eqAPIURL method to determine the appropriate API URL based on the source.

internal/config/equalize.go

@@ -2,19 +2,32 @@ package config
 
 import "os"
 
+const defaultExternalEQAPIURL = "https://autoeq.app/equalize"
+
 type EqualizeConfig struct {
-	APIURL string
+	APIURL         string // 内网 EQ 接口（正式环境 Eafonyoung 源使用）
+	ExternalAPIURL string // 公网 EQ 接口（正式环境非 Eafonyoung 源使用）
 }
 
 func loadEqualize(env string) EqualizeConfig {
+	external := getEnv("EQ_EXTERNAL_API_URL", defaultExternalEQAPIURL)
 	if os.Getenv("EQ_API_URL") != "" {
-		return EqualizeConfig{APIURL: os.Getenv("EQ_API_URL")}
+		return EqualizeConfig{
+			APIURL:         os.Getenv("EQ_API_URL"),
+			ExternalAPIURL: external,
+		}
 	}
 
 	switch env {
 	case "production":
-		return EqualizeConfig{APIURL: "http://172.31.18.70:8000/equalize"}
+		return EqualizeConfig{
+			APIURL:         "http://172.31.18.70:8000/equalize",
+			ExternalAPIURL: external,
+		}
 	default:
-		return EqualizeConfig{APIURL: "https://autoeq.app/equalize"}
+		return EqualizeConfig{
+			APIURL:         defaultExternalEQAPIURL,
+			ExternalAPIURL: external,
+		}
 	}
 }