refactor(frpc): replace ini with toml for config handling and improve proxy management

- Replace ini package with toml for more reliable config parsing
- Refactor proxy management to use structured config instead of string manipulation
- Add proper error handling for config operations
- Clean up unused imports and improve code organization
- Update go.mod dependencies accordingly

handlers.go

@@ -166,4 +166,4 @@ func LogRequest(r *http.Request, userID int) {
 
 func IntToString(i int) string {
 	return strconv.Itoa(i)
-}
+}