Draft: input module api refactor

applications/os will be ported in a seperate commit. check out the documentation page too!

biggest question: edge detection and pressed_since_ms imposes some light statefulness. previous state was user-configurable so that each instance of view needed its own input instance for repeats management.

this one still works like this due to backwards compatibility, but we're positive once we drop these compatibility layers we can turn this into a performant, lazy evaluated singleton that lives in C.

new repeats replacement demonstrated in AudioProcessor, all state it inflicts on ins is fleeting, view transitions clear it en passant.