fix: rewrite proxy links with token prefix and correct login redirect

- Add ModifyResponse to DynamicProxy to inject token-prefix JS and
  rewrite Location headers, same as GitHub proxy already did.
- Improve injectTokenPrefixScript to rewrite href/src/action on page
  load and watch for dynamically added elements via MutationObserver.
- Replace hardcoded ../ login redirect with pathname-based calculation
  so it works regardless of admin_path config.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <[email protected]>

internal/proxy/dynamic.go

@@ -1,11 +1,16 @@
 package proxy
 
 import (
+	"bytes"
 	"fmt"
+	"io"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
+	"strings"
 	"time"
+
+	"mirror-proxy/internal/auth"
 )
 
 // DynamicProxy 创建指向任意目标 URL 的反向代理
@@ -23,11 +28,48 @@ func DynamicProxy(targetURL string) http.Handler {
 			req.URL.Host = target.Host
 			req.Host = target.Host
 			req.Header.Set("Host", target.Host)
+			// 删除 Accept-Encoding，防止响应被压缩，便于修改 HTML
+			req.Header.Del("Accept-Encoding")
 			if req.Header.Get("User-Agent") == "" {
 				req.Header.Set("User-Agent", "MirrorProxy/1.0")
 			}
 			req.Header.Del("X-Forwarded-For")
 		},
+		ModifyResponse: func(resp *http.Response) error {
+			// 从请求上下文中获取 token 前缀
+			tokenPrefix := ""
+			if resp.Request != nil {
+				if prefix, ok := resp.Request.Context().Value(auth.TokenPrefixContextKey).(string); ok {
+					tokenPrefix = prefix
+				}
+			}
+
+			if tokenPrefix == "" {
+				return nil
+			}
+
+			// 重写 Location header
+			if loc := resp.Header.Get("Location"); loc != "" {
+				resp.Header.Set("Location", rewriteURL(loc, tokenPrefix))
+			}
+
+			// 对 HTML 响应注入 JS 脚本，重写链接
+			contentType := resp.Header.Get("Content-Type")
+			if strings.Contains(contentType, "text/html") && resp.Body != nil {
+				body, err := io.ReadAll(resp.Body)
+				if err != nil {
+					return err
+				}
+				resp.Body.Close()
+
+				body = injectTokenPrefixScript(body, tokenPrefix)
+				resp.Body = io.NopCloser(bytes.NewReader(body))
+				resp.ContentLength = int64(len(body))
+				resp.Header.Set("Content-Length", fmt.Sprintf("%d", len(body)))
+			}
+
+			return nil
+		},
 		ErrorHandler: func(w http.ResponseWriter, r *http.Request, err error) {
 			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 			w.WriteHeader(http.StatusBadGateway)