fix(ui): the platform layer speaks platform words; boxes scale with the text

- PriorityStepper labelled itself with channels.row.* and told every caller
  it orders the Feed; Combobox said plex.loading / plex.filter.moreRefine /
  sidebar.match on the feed sidebar. The generic strings moved to common.*,
  and what a priority MEANS arrives as the stepper's `hint` prop.
  uiI18n.contract.test.ts pins components/ui/ to the platform namespaces —
  the import boundary could never see an i18n key.
- 32 px-frozen box utilities (w-[150px], max-w-[1600px], left-[18px], …)
  became spacing-scale steps (w-37.5, max-w-400, left-4.5): identical at the
  default text size, and now they grow with the Settings slider instead of
  clipping or re-wrapping their own labels. An eslint rule refuses the px
  form beside the older text-[Npx] one, pinned by pxBox.contract.test.ts;
  measured in the browser that every new step is generated at its old px.
- chipLane's import-strip regex ran past a side-effect import into the next
  statement's `from`, hiding a lane between them; it now stops at the
  import's own `;`.

frontend/eslint.config.js

@@ -63,6 +63,12 @@ const jsxCommentText = {
 };
 const localRules = { rules: { "jsx-comment-text": jsxCommentText } };
 
+// A px-frozen BOX utility (the no-restricted-syntax block below): an esquery regex, as a string.
+const BOX_PX =
+  "/(^|[\\s:])(min-|max-)?(w|h|size|left|right|top|bottom|inset|gap|p[xytrbl]?|m[xytrbl]?)-\\[\\d+px\\]/";
+const BOX_PX_MESSAGE =
+  "px-frozen box size doesn't scale with --font-scale: use the spacing scale (w-37.5, max-w-60), not w-[Npx].";
+
 export default tseslint.config(
   { ignores: ["dist", "node_modules", "playwright-report", "test-results", "e2e/.auth"] },
   {
@@ -107,7 +113,7 @@ export default tseslint.config(
       // R10 S2: keep the rem system from rotting. A px-frozen `text-[Npx]` font size does NOT scale
       // with the Settings --font-scale slider while its rem neighbours do; use `text-2xs`/`text-3xs`
       // or a `text-[Nrem]` arbitrary instead. Matches both plain strings and template-literal chunks;
-      // rem arbitraries (text-[0.75rem]) don't match (no "px"). Font-size `text-` only — not w-/h-/p-.
+      // rem arbitraries (text-[0.75rem]) don't match (no "px").
       "no-restricted-syntax": [
         "error",
         {
@@ -120,6 +126,11 @@ export default tseslint.config(
           message:
             "px-frozen font size doesn't scale with --font-scale: use text-2xs/text-3xs or text-[Nrem], not text-[Npx] (R10 S2).",
         },
+        // …and the same for a BOX: a `w-[150px]` stays 150px while the text inside it grows with the
+        // slider, so the label re-wraps or clips at large sizes. Use the spacing scale (`w-37.5` is
+        // 150px at the default size) — 32 of these were swept in the 2026-09 debt burn.
+        { selector: `Literal[value=${BOX_PX}]`, message: BOX_PX_MESSAGE },
+        { selector: `TemplateElement[value.raw=${BOX_PX}]`, message: BOX_PX_MESSAGE },
       ],
     },
   },