Add larger-client layouts, cmd arguments, and new action types

[MohammedSalem2510]

The fixed 100px 5x3 grid only fills part of the screen on DeskThing clients bigger than the Car Thing's 800x480 (tablets, Echo Show).

• Add three layout options: the existing 5x3, a 5x3 scaled to fill the display, and a 7x5 grid of 35 buttons (the original 15 stay centred and unchanged; the new 20 fill the outer ring clockwise from the top-left), selectable from settings
• Support arguments in cmd actions, so a wrapper script is no longer needed to pass parameters
• Add three action types alongside cmd: key for a global keystroke, url to open a link, and dt to fire a DeskThing action such as dt,server,play or dt,discord,mute
• Run commands on Windows as well as Linux, and add windows to the manifest platforms