Trim needless comments and fix the picker width

Remove comments that only restate the code, keeping the section banners
and the notes that carry a reason, a measured fact or an external
contract.

ButtonOptions.width claimed to be a fixed width but only set minWidth,
so the Graph and Texture pickers grew with the name they showed. It is
now what it promises, with a separate minWidth for the buttons that have
two forms. Narrow buttons shrink their padding, otherwise a 24px icon
button had 8px left for its glyph and truncate dropped it entirely.

__gm.labelsDropped() guards that class: the overflow guard only saw text
that was too wide, never a label truncated to nothing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -269,8 +269,14 @@ selected and switched back on.
   `Label.ts`, shared by `Label`, `ListRow` and `Button`). A `Button` keeps the full text and
   measures from it – only what is drawn is shortened – and a subclass that puts something else
   inside the control takes its room off `labelSlot()`, so a long value is cut rather than run
-  underneath the chevron. `__gm.textOverflows()` guards the whole class of bug: it reports any
-  visible text drawn wider than the widget owning it (e2e step 14).
+  underneath the chevron. Given a `width`, a button is exactly that wide and truncates instead:
+  the tab-bar buttons and the Graph and Texture pickers keep their size whatever they show.
+  The padding is an inset rather than a claim, so a 24 px icon button spends it on the glyph
+  instead of truncating it away; a button that switches between label forms (`↺` and `↺ ▾`) asks
+  for `minWidth` and grows. `__gm.textOverflows()` guards the whole class of bug: it reports any
+  visible text drawn wider than the widget owning it, `__gm.labelsDropped()` guards the other
+  direction – a button too narrow to draw any of its label – and `__gm.graph.pickerWidth()` /
+  `__gm.texture.pickerWidth()` catch a picker that resizes itself around its content (e2e step 14).
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