BUILDER.md's review round assumed ready-throughout, so a builder or
reviewer meeting a mid-round draft found behaviour the doctrine never
described. Three points, doctrine not mechanism: the draft phase stays
the builder's through a fix round, ready-for-review is the builder's own
act and no engine's, and where the draft suppressed CI green is proven
at the flip with the request following it — step 1's rule at a stated
moment, not a second rule.
REVIEWER.md gains the reading that keeps a reviewer from misfiling it:
a draft carrying state:addressing is a fix round in progress.
Refs #258
