TEXTURES.md: exercise grow_array (a second atlas layer opening) on tabs

Reasoned through but never watched happen, per the file's own "Not
separately stress-tested" note. Temporarily dropped PAGE from 1024 to
64 so tabs's ordinary mix of text sizes/families already exceeds one
page; a throwaway eprintln in grow_array confirmed two real grows in
one run (1->2, 2->4 layers), and run-headless.sh showed every tab's
text rendering correctly across layers, with no corruption. Both
temporary changes reverted; tabs and minimal confirmed byte-identical
to the pre-check screenshots afterward.

Co-Authored-By: Claude Sonnet <noreply@anthropic.com>

RUST.md

@@ -52,11 +52,12 @@ session spending an afternoon on them again.
   pixel-identically to before the change. See LAYOUT.md's "Deviations
   found during implementation" for five real bugs the design's first draft
   did not anticipate — worth reading before touching `Aligned`, `Sized`,
-  `MaxSize`, `Scroll`, or the move-slot lifecycle again. Not done: a
-  pixel-level screenshot check of a `Masked`-wrapped `Scroll` (no example
-  builds one yet — the numeric check in `layout_tests.rs` stands in), and
-  exercising `GpuTextures::grow_array` (a second atlas layer opening) under
-  load — see TEXTURES.md.
+  `MaxSize`, `Scroll`, or the move-slot lifecycle again. `GpuTextures::grow_array`
+  (a second atlas layer opening) has now been exercised too, on `tabs` with
+  `PAGE` temporarily lowered — see TEXTURES.md's "Exercised, 2026-09-04".
+  Not done: a pixel-level screenshot check of a `Masked`-wrapped `Scroll`
+  (no example builds one yet — the numeric check in `layout_tests.rs`
+  stands in).
 - **E1's keyboard gap is Masonry's `as_input_connection` returning `None`
   (a TODO), not android-view or `EditorInfo`.** android-view's own demo
   implements the `InputConnection` trait over a parley editor and gets