rust-cleanup by alb-o/pw-rs

review the current work for inline comments, consolidate useful technical information into proper rustdoc docstrings:

remove trivial inline comments
move comments explaining why or tech specs into rust docstrings
follow rustdoc conventions: Use # Examples, # Panics, # Errors, # Safety sections where appropriate
treat docstrings as tech specs with additional (start simple first line(s), move to spec lower, with intra-doc links)
remove implementation-specific qualifiers and trailing parenthesized text
remove comments used for section markers
do NOT outright remove docstrings, especially from pubs
MUST keep docstrings thorough and technical

check for tramp data, unecessary vars that could be inlined, performative error handling, etc.
prefer data-oriented orthogonal approaches