docs: P3 -- the boot runs unattended, and four answers taken as given

Gate: `godot --path port -- --boot --film=/tmp/boot` runs publisher_logo ->
developer_logos (4.65 s) -> title (8.57 s), holding on the title after 13.05 s,
each screen fading in, holding, and fading through black into the next.

verify-screen now covers all 16 screens and passes `--all` to the reference
renderer: the exporter addresses by pak entry index, which is the numbering
`--all` uses, and without it `--build 10` would land on entry 12. The four new
splash bundles come in at max 1-2/255. The three known differences are unchanged.

Also recorded, taken from the RE agent rather than re-derived:

* Focus stays "replace" -- over-vs-instead is unobservable (the focused sprite
  covers the base at 100 % of base-visible pixels; the two compositions differ by
  RMSE 1.1, under the gamma floor). The port guessed right for the wrong reason.
  The real gap is that ptbtn0Nf.rat declares TWO sprites -- a glowing ring, then
  the label -- where ptbtn0N.rat declares one. P5's, and the ring's placement is
  not decoded, so it will be authored from the capture and marked as such.
* RMSE against captures has a FLOOR: capture ~ 255*(render/255)^g, g ~ 1.49 menu
  and EXTRAS, 1.34 title, and it is a ramp the GAME installed, not a capture-path
  artefact to subtract. Narrow reach (fitted on mostly-dark patches), so the port
  will not extrapolate it and will not apply it to rendered output. It is a
  comparison constant, not a rendering one.
* Rotation is escalated to a human and the port has NOT acted. The RE half is
  answered -- about the declared pivot, measured -- and it has zero effect on the
  five screens at rest.

tools/verify-screen

@@ -65,8 +65,12 @@ m=json.load(open("export/manifest.json"))
 f=next(s["file"] for s in m["screens"] if s["name"]==sys.argv[1])
 print(json.load(open("export/"+f))["source"]["build"])' "$name")
 
+  # `--all` because the exporter now addresses by PAK ENTRY INDEX, which is the
+  # numbering `--all` uses; without it the CLI enumerates only the 12 bundles
+  # `is_build` accepts and `--build 10` would land on entry 12. `--all` widens
+  # the list, it does not change how any one bundle composites.
   "$CLI" screen render "$DISC/dat/GP_TITLE.pak" "$OUT/$name.ref.png" \
-    --build "$build" --black --primitives --animated >/dev/null
+    --build "$build" --all --black --primitives --animated >/dev/null
 
   godot --path port --resolution 1280x720 -- \
     "--screen=$name" --pose=rest "--capture=$OUT/$name.godot.png" >"$OUT/$name.log" 2>&1