feat(httpc): go-hua/httpurl 迁入并更名 httpc(HTTP 客户端)

- 原包名 httpurl 看不出是客户端, 更名 httpc; GET/POST/PUT/DELETE/代理/
  Digest 认证, 函数签名不变, 附测试、例程与 README

examples/httpc/main.go

@@ -0,0 +1,47 @@
+// httpc 包示例：HTTP 客户端封装（Get/Post/Put/Delete/GetProxy/DigestAuthRequest）
+package main
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+
+	"git.zeroonesoft.cn/golib/zogo/httpc"
+)
+
+func main() {
+	// 启动一个本地测试服务
+	mux := http.NewServeMux()
+	mux.HandleFunc("/get", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, `{"method":"%s","query":"%s"}`, r.Method, r.URL.RawQuery)
+	})
+	mux.HandleFunc("/post", func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		fmt.Fprintf(w, `{"method":"%s","body":%s}`, r.Method, string(body))
+	})
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		panic(err)
+	}
+	go http.Serve(l, mux)
+	base := "http://" + l.Addr().String()
+
+	// GET
+	body, err := httpc.Get(base+"/get?name=go-hua", nil)
+	fmt.Println("GET:", string(body), "err:", err)
+
+	// POST（默认 Content-Type: application/json）
+	body, err = httpc.Post(base+"/post", []byte(`{"id":1}`), nil)
+	fmt.Println("POST:", string(body), "err:", err)
+
+	// 带自定义请求头
+	body, err = httpc.Get(base+"/get", map[string]string{"X-Token": "abc123"})
+	fmt.Println("GET(带Header):", string(body), "err:", err)
+
+	// 其他方法用法相同：
+	// httpc.Put(url, param, header)
+	// httpc.Delete(url, param, header)
+	// httpc.GetProxy(url, header, "http://127.0.0.1:7890")
+	// httpc.DigestAuthRequest(&httpc.RequestArg{...})
+}