re(ui): finish the top-level rotation census; record the JP-capture blocker

Two threads had converged on needing one capture this container cannot
take, so this iteration records that and finishes something reachable.

BLOCKED, written into MISSION.md rather than worked around: Q1's keyframe
time association and the rest() rule for plateau-less elements both now
hinge on a running capture of GP_TITLE build 7, the Japanese title. The
console language is not settable here -- user_language appears only as
DECLARE_int32 at four call sites with no DEFINE anywhere in the tree, and
it is absent from the registered cvars in xenia-canary.config.toml. There
is no flag to pass, and guessing one is specifically unsafe: run-canary's
own header records that xenia calls ShowSimpleMessageBox from
ParseLaunchArguments before logging starts, so a bad flag blocks forever
with an empty log. Rebuilding canary to add the cvar would be improvising
around the blocker; it needs a human decision. Neither question blocks
the five menu screens.

FINISHED: the disc-wide top-level rotation count, left running four
iterations ago as a shell loop over `screen info --geometry` that never
completed (it decodes every texture per build). Walking the placement
region directly takes seconds.

  top-level elements with a keyframe group   15 493
  carrying a non-zero rotation                2 152  (13.89 %)

Both controls pass: GP_TITLE build 4 reports 0 (its rotations are the
nested ptloop records) and GP_DIALOG build 0 reports the expected two.

The control earned its place -- the first version indexed the pak with a
`screen list` BUILD number and got 0 for a screen that has two, because
GP_DIALOG build 0 is entry 2. GP_TITLE maps 1:1, which is how the
assumption survived. METHOD line added.

Two free corroborations of the rotation decode. The rotated population is
dominated by tactical-map ship icons -- pbb_destroyer 444, pbr_destroyer
402, pbr_fighter 276 -- i.e. markers rotated to heading, the single
largest use of the field on the disc. And GP_TITLE entry 7's Japanese
wordmark pieces settle from ALTERNATING tilts:

  ptlogo3a  r = 0, -14, -4, -1, 0, ...
  ptlogo3b  r = 0, +14, +4, +1, 0, ...
  ptlogo3c  r = 0, -14, -4, -1, 0, ...

Same magnitudes, opposite signs, all decaying to upright. A misread field
does not produce that.

docs/port/MISSION.md

@@ -77,6 +77,37 @@ alongside it.
 | **Q10** | **What are a music bank's sub-waves?** `BGM_001.slb` is three sub-waves — 10 KB, 4.47 MB, 4.67 MB — and we currently **concatenate them blindly** into one 347 s track. Two near-equal halves could be intro + loop, or two variations, or two halves of one piece. A menu that loops its music needs to know which | The role of each sub-wave, established for at least the menu BGM. "Concatenate" is a decision, not a default — right now it is a default nobody chose |
 | **S1** | ~~**Ready Room probe.**~~ **DONE 2026-08-28 — [no-go](../re/ready-room-probe.md).** It is 2D and enumerates fine, but the pak is briefing/tactical-map content, not the Ready Room menu | ✅ go/no-go written |
 
+## 🔴 Blocked in this container — a Japanese-locale capture
+
+Recorded rather than worked around, per "do not improvise around a blocker".
+
+Two questions have converged on needing **one capture we cannot take**: a running
+capture of `GP_TITLE` **build 7**, the Japanese title screen.
+
+* Q1's keyframe-time association. The shifted reading is favoured 26× by a
+  calibration-free measurement, and the only render it changes on the whole disc
+  is build 7 ([`ui-keyframe-time-unit.md`](../re/ui-keyframe-time-unit.md)).
+* What `rest()` should return for a plateau-less element. The one element that
+  discriminates, `ptlogo_eff3.t32`, is also in build 7
+  ([`structures/ui-resting-pose.md`](../re/structures/ui-resting-pose.md)).
+
+**Why the container cannot do it:** the console language is not settable. In this
+canary tree `user_language` appears only as `DECLARE_int32` — four call sites,
+no `DEFINE` — and it is absent from the registered cvars in
+`xenia-canary.config.toml`. There is no flag to pass, and passing an unknown one
+is specifically dangerous here: `run-canary`'s own header records that xenia
+calls `ShowSimpleMessageBox` from `ParseLaunchArguments` *before* logging starts,
+so a bad flag blocks forever on an SDL dialog with an empty log.
+
+Rebuilding canary to add the cvar would be improvising around this, so it has not
+been done. **It needs a human decision**: either add the cvar and rebuild, or
+accept that both questions stay 🟡 and the port authors those values by hand.
+
+⚠️ Neither question blocks the five menu screens. Q1's *interpolation law* is
+settled and only multi-keyframe absolute timing is open; `rest()` differs from
+its alternative on **one** element across all five screens, and the current
+answer there is the defensible one.
+
 ## Known unknowns — say so, do not fill them in
 
 Some of these may turn out to be undecodable. That is a valid, useful answer, and