is there a such thing as 'no modifier'?

Coming from i3/sway, I am use to entering "resize mode" by pressing `mod - r` at which point 'hjkl' act as resize modifiers. This was nice as I didn't have to hold down any modifier keys while adjusting my window sizes.

I was able to get `modes` figured out with skhd (to enter resize modes) but it seems all shortcuts still require you press and hold a modifier key. Just wonder if there was as way to stipulate 'no modifier' somehow so you can do stuff like:

```
# resize mode
:: default
:: grow
:: shrink

alt - r ; grow
grow < alt - r ; default

shift + alt - r ; shrink
grow < shift + alt - r ; default

# resize managed window
grow < h : yabai -m window --resize left:-20:0
grow < l : yabai -m window --resize right:20:0
grow < j : yabai -m window --resize bottom:0:20
grow < k : yabai -m window --resize top:0:-20

shrink < h : yabai -m window --resize left:20:0
shrink < l : yabai -m window --resize right:-20:0
shrink < j : yabai -m window --resize bottom:0:-20
shrink < k : yabai -m window --resize top:0:20
```

Start with skhd's mode syntax and the configuration examples in the issue, then trace how shortcuts are parsed and matched inside the daemon. Done means a mode can bind h, j, k, and l without a held modifier while retaining the shown grow and shrink transitions.

Written by the indexing model from the issue text.