docs: the suite is heavy, not hung -- correcting my own "cannot terminate"

Last iteration I wrote that build-reborn test cannot finish in a working
session, from having watched it run 3h26m. That was the stronger claim
and I made it without measuring the work.

Timing `mesh info` on each of the 166 .xpr containers with a 25 s cap:

  files scanned                166
  exceeding 25 s                19   Hangar, 17 Stage_*, ptc_pack
  Stage_S02 to completion      144 s, rc = 0

Nothing hangs. Nineteen heavy containers at roughly two minutes each is
about 45-60 minutes for one pass, before the 147 fast ones. The 3h26m
observed was that hour of work running at a load average of 9-14 --
inflated by the two duplicate runs I had left going, which did not merely
coexist with the slowness but multiplied it.

The practical conclusion is unchanged and only the wording softens: an
hour-scale suite is not an iteration-scale gate, and every "green" I
reported from it this session was partial. But an hour-scale gate can be
run deliberately, whereas a hung one cannot be run at all, so the
distinction is worth having right.

File list committed as reference data so the cost is attributable without
re-scanning.

METHOD: a slow thing observed under contention looks like a stuck thing;
measure the work before choosing between "cannot finish" and "takes an
hour".

docs/re/METHOD.md

@@ -734,3 +734,11 @@ agent's loop prompt, i.e. nowhere durable. See [`README.md`](README.md) for the
   suite is stated to have terminated — so report the suite count and elapsed
   state rather than the word "green", which is what I should have been doing all
   session.
+* **"Cannot finish" and "takes an hour" are different claims — measure before
+  choosing.** I wrote that the verification gate *cannot terminate*, from having
+  watched it run 3 h 26 m. Timing the work directly: 19 of 166 containers exceed
+  25 s, `Stage_S02` completes in **144 s**, and one full pass is ~45–60 minutes.
+  Nothing hangs. The 3 h 26 m was that hour of work at a load average of 9–14,
+  inflated by my own duplicate runs. A slow thing observed under contention looks
+  like a stuck thing, and the correction matters: an hour-scale gate can be run
+  deliberately, a hung one cannot be run at all.