refactor(api): fetchAllConfigs 接口从 GET 改为 POST

- 服务端: 新增 FetchAllRequest 结构体，参数通过 JSON body 传递
- 服务端: 路由从 api.GET 改为 api.POST
- Go/Python/Node.js/Java 客户端同步更新为 POST + JSON body
- 与 fetchChangedConfigs 接口风格统一，token 不再暴露在 URL 中

go-client/client.go

@@ -1,6 +1,7 @@
 package client
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -107,14 +108,26 @@ func (c *Client) Stop() {
 }
 
 func (c *Client) fetchAll() error {
-	url := fmt.Sprintf("%s/api/fetchAllConfigs?appName=%s&env=%s&version=%s&ignoreGlobal=%v",
-		c.config.BaseURL, c.config.AppName, c.config.Env, c.config.Version, c.config.IgnoreGlobal)
+	url := fmt.Sprintf("%s/api/fetchAllConfigs", c.config.BaseURL)
 
-	req, err := http.NewRequest("GET", url, nil)
+	payload := map[string]interface{}{
+		"appName":      c.config.AppName,
+		"env":          c.config.Env,
+		"version":      c.config.Version,
+		"ignoreGlobal": c.config.IgnoreGlobal,
+		"token":        c.config.Token,
+	}
+	payloadBytes, err := json.Marshal(payload)
 	if err != nil {
 		return err
 	}
 
+	req, err := http.NewRequest("POST", url, bytes.NewReader(payloadBytes))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
 		return err