re(ui): a RATC child's name is stated, not inferred -- and it was hiding every menu background

`ratc::parse` named each child by scanning backwards for the last printable run
of bytes before its magic. The format states the name explicitly instead, in an
`opt ` block: `"opt " | BE32 len | name | NUL | 3 bytes | magic` -- the same
block `ui_layout::opt_link` already read for a button's focus link.

The scan agrees with it 17 918 times out of 17 942 and is wrong 24 times, every
one the same failure: the 3 trailing payload bytes are themselves printable and
beat the real name. For `pteff05.t32` those bytes are `38 41 58` = `8AX`, so the
full-resolution background of all five menu screens registered under a name no
element declares, resolved to no sprite, and `compose` dropped it through an
early `continue` that -- unlike the two arms above it -- records nothing. The
screen lost its background and `screen render` still reported "all resolved".

`8AX` was never a name. Docs that treated it as one are corrected here.

Disc-wide, and the control is the 17 918 the scan already got right: the `opt `
reading reproduces every one of them. Effect on the five screens is the
signature of the same art at twice the resolution -- mean brightness unmoved,
high-frequency detail x1.15..x1.30 -- which is what the separately-measured
`ui-8ax-fullres-background` result said the game draws.

Also closes a long-standing dangling reference: `pmbase.t32`, recorded as "on
the disc nowhere", is the `GP_STAGE_CLEAR` child the scan called `8AX`. RATC
sibling references now resolve 10 148 of 10 148.

Verified: 114/114 sylpheed-formats unit tests (including two new ones pinning
the `8AX` case byte for byte and the no-block fallback), and every disc-gated
integration suite in sylpheed-formats/sylpheed-cli.

docs/re/REFUTED.md

@@ -605,3 +605,15 @@ neighbourhood, not just the line.
   them regardless. The no-overlap measurement was correct; the inference from it
   was not. What survives: a capture of this screen can only cross-check the order
   *within* each half. [`ui-prm-primitives.md`](structures/ui-prm-primitives.md)
+
+* "`8AX` is the name a `T8aD` is registered under" → **it is not a name at all.**
+  It is three bytes of the preceding record's payload (`38 41 58`) that happen to
+  be printable ASCII, which our backwards printable-run scan preferred over the
+  name the format actually states in its `opt ` block. The claim sat in
+  `HANDOFF.md` and `ui-8ax-fullres-background.md` as though `8AX` were a real
+  identifier, and cost every menu screen its full-resolution background.
+  [`ratc-child-names.md`](structures/ratc-child-names.md)
+* "`pmbase.t32` is on the disc nowhere" (the one dangling asset behind
+  `10 144 of 10 148 references resolve`) → **withdrawn; it is on the disc.** It is
+  the `GP_STAGE_CLEAR` child the same scan named `8AX`. With the name decoded the
+  count is **10 148 of 10 148**. [`ratc-child-names.md`](structures/ratc-child-names.md)