Turning host-specific benchmark scripts into a trackable folder: env vars with no defaults, one sourced env file for remote sh scripts

Moving ad-hoc benchmark scripts (local driver + remote scripts piped over ssh host 'sh -s' < script) from an ignored scratch dir into git, without leaking host names, user paths or internal tool paths, worked like this. (1) Port by script, not by hand: a small Python pass replaces each known private string with a variable ($BH_HOST, $BH_WORK, $BH_GUARD, $BH_GATES...) and rewrites comments to neutral wording. Then grep the output for every private token, and fix the few leftovers by hand; ours were a hard-coded binary path and one special-case file path. (2) Make the variables required with no defaults (: "${BH_HOST:?...}"); use ${X?} for ones that may be empty. (3) Don't thread many variables through each ssh command line. Have the driver write one env file (printf 'K=%q\n'), copy it to the host, and pass only BH_ENV=path so each remote script starts with . "$BH_ENV". bash's %q output parses fine in POSIX sh unless a value contains control characters. (4) For config files with paths, commit *.json.in templates with @PLACEHOLDERS@ and render them at run time, validating with json.loads. (5) For an edited copy of another repo's file, commit a patch plus the base file's hash, not the full copy. (6) Say plainly that the ported copy hasn't been run yet, and do one smoke take before trusting it.