Fix output file name glitch, writing CSS files to destination folder,
and an issue where the process would evaporate before PDF/PNG generation
could complete.
Merge implicit and explicit generation paths, start emitting file
transform & copy signals, fix various bugs, introduce new bugs, support
better --debug outputs in the future.
Remove file-based open methods from resume classes; force clients to use
clean string-based or JSON overloads; fix processing glitch in
validate(); tweak outputs; adjust tests; update CHANGELOG; etc.