`while IFS='=' read -r k v` drops an unterminated final line: read returns
1 at EOF even having filled k and v. A manifest ending `bootstrapped=...Z`
with no trailing \n rendered `RIG 1.2.3` with the timestamp silently gone
— the version read fine, so nothing looked wrong.
Guarded with `|| [ -n "$k" ]`, the same shape parse_users_file already
uses (lib/users-config.sh:47). #61's writer should not have to know
whether this reader tolerates a missing newline.
Also make human_b fall back like human_kb. With numfmt absent, memory
degraded to a raw number while disk printed 'unknown' beside it, from data
already in hand.
Both found in review of #74.
Refs #64
3cfbb8921c