Main README: clone/SSH/branching quickstart with full /das paths,
--tmpdir/--distdir as part of the standard build command (do not fill
/var/tmp or $HOME) with cleanup for defaults, tips deduplicated against
module READMEs, old-system references removed, resource links and
tutorial acknowledgements added.
Module READMEs: purge outdated recipes repo-wide — Pmodules/1.1.20 and
2.0.0 plus ./build replaced by modbuild/2.1.3 invocations; the cctbx
unbound-variable fix moved from the main README into phenix and DIALS
READMEs where it belongs.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>