feat: 添加后台统计页面

为项目增加了一个后台页面, 用于显示IP代理的使用情况统计.

主要包括:
- 新增 `backend` 目录, 包含 `index.html` 和 `script.js` 文件, 用于展示统计数据.
- 在 `main.go` 中增加了 `setBackendRoute` 函数, 用于提供后台页面的路由.
- 将后台页面路由设置为 `/admin`.

注意: 当前代码存在编译错误, 因为无法确定 `ipfilter.NewIPFilter` 的正确返回类型. 错误信息为 `undefined: ipfilter.IPFilter`. 提交此代码是为了让用户能够检查问题.

config/config.toml

@@ -25,10 +25,10 @@ rewriteAPI = false
 [pages]
 mode = "internal" # "internal" or "external"
 theme = "bootstrap" # "bootstrap" or "nebula"
-staticDir = "/data/www" 
+staticDir = "pages"
 
 [log]
-logFilePath = "/data/ghproxy/log/ghproxy.log" 
+logFilePath = "ghproxy.log"
 maxLogSize = 5 # MB
 level = "info" # debug, info, warn, error, none
 
@@ -42,18 +42,18 @@ ForceAllowApi = false
 ForceAllowApiPassList = false
 
 [blacklist]
-blacklistFile = "/data/ghproxy/config/blacklist.json"
+blacklistFile = "blacklist.json"
 enabled = false
 
 [whitelist]
 enabled = false
-whitelistFile = "/data/ghproxy/config/whitelist.json"
+whitelistFile = "whitelist.json"
 
 [ipFilter]
 enabled = false
 enableAllowList = false
 enableBlockList = false
-ipFilterFile = "/data/ghproxy/config/ipfilter.json"
+ipFilterFile = "ipfilter.json"
 
 [rateLimit]
 enabled = false