re(ui): rotation is not nested-only, and the pivot-anchored scale is measured

Two corrections and one new confirmation, all from finishing the sweep I
left running last iteration.

Refuted, by my own sweep, within the hour: "rotation appears to live only
in nested .rat leaf records". That held for GP_TITLE, GP_BUNK and
GP_CHALLENGE -- the three archives the sweep had reached when I wrote it
-- and fails on GP_DIALOG and GP_DEBRIEFING_PILOTLOG, which rotate
top-level elements. Scoping the claim made it cheap to withdraw, but the
sentence should have waited for the sweep.

Those top-level cases are the best evidence on the disc, and they show up
in `screen info --geometry` without a hex dump. GP_DIALOG build 0:
pceff03/pceff04 ramp r = 90 -> 30 -> 10 -> 3 -> 0 while alpha ramps
0 -> 255 and they slide into place -- a swing-in settling upright. Build
6: pzeff02 ramps 43 -> 61 -> 75 -> 90 while scaling 112% -> 200% and
fading to 0 -- a spin-out. Rows committed as reference data.

New: the pivot-anchored scale term in blit, kf.x - pivot*(scale-100)/100,
was implemented and reasoned about but never measured, because every
element previously examined sits at 100% scale where the term is exactly
zero. The ptloop pair scale 600% and 800%, where it is worth 450 and 630
px. Formula predicts centre y = 360.0 for both; capture measures 359.1
and 360.0. Top-left anchoring predicts 810 and 990. Horizontally it makes
t-from-position agree with t-from-alpha to 0.33 / 0.65 units against ~8
without it.

That agreement does NOT prove linear interpolation -- both fields were
inverted through the same linear map, so a shared easing curve cancels.
It shows position and alpha ride one shared parameter. Recorded as such.

The disc-wide sweep is still running; the count is incomplete, the
existence is settled.

docs/re/REFUTED.md

@@ -59,6 +59,17 @@ neighbourhood, not just the line.
 * "a keyframe-block scanner may assume 4-byte alignment" → refuted; it found
   **0/3** of its own control blocks and under-counted the corpus by 16 341
   blocks. Nested `RATC` blobs start at odd offsets (`0xbb5966`).
+* "keyframe rotation lives only in **nested** `.rat` leaf records" → **mine, and
+  refuted within the hour by my own sweep.** It held for the three archives I had
+  checked (`GP_TITLE`, `GP_BUNK`, `GP_CHALLENGE`) and failed on the next:
+  `GP_DIALOG` and `GP_DEBRIEFING_PILOTLOG` rotate **top-level** elements, and
+  those are the clearest examples on the disc.
+  [`ui-keyframe-rotation.md`](structures/ui-keyframe-rotation.md)
+* "the pivot-anchored scale formula `kf.x − pivot·(scale−100)/100` is our
+  renderer's reading, not a measurement" → **now measured.** At the `ptloop`
+  pair's 600 %/800 % scale it predicts both quad centres at y = 360.0 against a
+  captured 359.1/360.0, where top-left anchoring predicts 810/990.
+  [`ui-keyframe-rotation.md`](structures/ui-keyframe-rotation.md)
 * "the game passes a pink per-vertex colour for the title swoosh" → **refuted by
   draw capture.** Every vertex colour in the capture is `<alpha>FFFFFF`, white RGB.
 * "the swoosh discrepancy is undecodable" → **solved**: the game submits it as two