Add a hour counter for each file

[short saffron]

A message in the menu, or a small counter at the top that marks the number of hours you've been working at that particular piece.

[red seal]

that'd be kinda cool

but also a bit out of scope, could this be an extension?

@placid monolith can we let extensions write custom data to .pixi ?

[placid monolith]

That's a good question, we gotta discuss about it

[red seal]

I can't come up with any downsides

it could be just some key value storage thing that doesn't participate in undo and that is simply serialized with everything else