feat: Adding path support for disk storage display

[Walter0697]

The current implementation only read disk storage for the root path "/'
I added support for it so that you can optionally custom define path for your theme
It is more important for me to know the mounted storage in my use case that's why I want this functionality

For the theme setting, we can have the additional PATH attribute for DISK in theme.yaml

STAT:
  DISK:
    INTERVAL: 10
    PATH: /mnt/data            # ← New optional parameter
    USED:
      RADIAL:
        SHOW: True
        X: 225
        Y: 385