feat(client): 配置拉取请求中添加 token 认证字段

- 请求 payload 中新增 token 字段，将配置中的 Token 传递给服务端
- 新增 client_test.go 验证 fetchChanged 正确发送 token 和 lastTime

kenaito-conf-go-client/client_test.go

@@ -0,0 +1,43 @@
+package client
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestFetchChangedSendsToken(t *testing.T) {
+	var received map[string]interface{}
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/api/fetchChangedConfigs" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		if err := json.NewDecoder(r.Body).Decode(&received); err != nil {
+			t.Errorf("decode request body: %v", err)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"code":0,"data":{}}`))
+	}))
+	defer srv.Close()
+
+	c := New(&Config{
+		BaseURL: srv.URL,
+		AppName: "demo-app",
+		Env:     "daily",
+		Token:   "test-token",
+	})
+	c.lastTime = 1699999999999
+
+	if err := c.fetchChanged(); err != nil {
+		t.Fatalf("fetchChanged() error = %v", err)
+	}
+
+	if got := received["token"]; got != "test-token" {
+		t.Fatalf("token = %v, want %q", got, "test-token")
+	}
+	if got := received["lastTime"]; got != float64(1699999999999) {
+		t.Fatalf("lastTime = %v, want %v", got, 1699999999999)
+	}
+}