re(ui): kill two candidate meanings for the T8aD 0x02 bit, and fix attribution

The bit at +0x04 was recorded as a real field with its meaning "not
diagnosed", noting ptlogo_back2eff is 0x8830 "despite its name". That note
rested on a size match -- and its size is ambiguous, which is the trap
this corpus already records.

First, a sound attribution. T8aD headers appear in the bundle in RATC
CHILD ORDER, verified on GP_TITLE build 4 against an independent property
-- each header's decoded dimensions versus the dimensions the named child
should have: 18 of 18 match, 0 mismatches. Two of those eighteen share a
size (ptlogo_back2eff and ptlogo_back2eff5, both 1133x280), so a size-keyed
lookup cannot separate them; ordering can. Index 12 is back2eff5 (0x8832,
bit set), index 14 is back2eff (0x8830, bit clear). The documented
counterexample is real and correctly attributed -- now on evidence.

Two candidate meanings tested and refuted:

  bit <=> name contains "eff"        REFUTED: ptlogo_back2eff is an eff
                                     name with the bit clear. All 10
                                     bit-set sprites are eff names, so
                                     the implication holds one way only.
  bit <=> the element is transient   REFUTED: pteff03/pteff03a carry the
                                     bit and run to t=250, ramping to
                                     a=255 and holding.

Up close, the exception pair differs in two header words: +0x04
0x8832/0x8830 and +0x08 0x8083/0x8081 -- layer keys 32899 and 32897. They
are NOT duplicates: their alpha summaries agree to one decimal (4.5%
opaque, 86.7% clear, mean 19.3) but a pixel compare gives max abs diff 21.
Two renditions of one image at one size, which is why the summaries were
not trusted.

Still not diagnosed, and said so -- but the search space is two smaller
and the attribution beneath it is now sound.

METHOD: T8aD headers sit in child order, use that not the size; and
identical summary statistics are not identical data.

docs/re/REFUTED.md

@@ -496,3 +496,12 @@ neighbourhood, not just the line.
   `_stream.xtr` appears **once** in the Debug binary and **zero** times in the
   Release binary `run-canary` actually uses.
   [`capture-harness-status.md`](capture-harness-status.md)
+* "the `T8aD` `+0x04` bit `0x02` means the sprite's name contains `eff`" →
+  **refuted, now on evidence.** `ptlogo_back2eff` is an `eff` name with the bit
+  clear; the attribution is confirmed by header-order pairing (18/18 on build 4)
+  rather than by a size match, which cannot separate it from the same-sized
+  `ptlogo_back2eff5`. All 10 bit-set sprites *are* `eff` names, so the
+  implication runs one way only.
+* "the bit `0x02` marks a transient element" → **refuted.** `pteff03` and
+  `pteff03a` carry the bit and run to `t=250`, ramping to `a=255` and holding.
+  [`ui-paint-order-key.md`](structures/ui-paint-order-key.md)