[feature] Fix URL filter to enable local files / feature extensions

[alfablend]

Version and OS
0.46.04 on Windows

Is your feature request related to a problem? Please describe.

I need to monitor changes in local text file "text.txt". This file is regullary updated by my own script (that compile data from several sources, for example, content of recently downloaded pdf files after ocr).

File "test.txt" is stored in changedetection.io app "static" folder and so it's accessible via browser by http://localhost:5000/test.txt.

Unfortunatly when I try to add task in changedetection.io app edit interface with URL "http://localhost:5000/test.txt" I have error "Invalid template syntax"

Describe the solution you'd like

Please make possible to add localhost or 127.0.0.1 addresses in edit interface

Describe the use-case and give concrete real-world examples
See screenshort

Additional context
Meanwhile, I can add local file monitor task from app main page - it has not url filter that blocks local tasks.