finalize file format

[haberdashPI]

• use a non recursive format; where we would nest things before, use a path field. This should be more forgiving when using JSON instead of TOML, simplifies validation and zod types, etc...

• replace do.command with command, and use runCommands for multiple commands to make the format consistent with normal keybindings / one could even copy normal keybindings to the file

• make it an error/warning to create bindings that interfere with UX in VSCode: i.e. bindings without a modifier key have to require editor focus (where shift alone doesn't count)

• convert zod types in to schema for keybinding validation that can show up as a file is being written

[haberdashPI]

Not really using issues to track stuff right now. See notes.md / README.md