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/src/components/VideoInfoCard.tsx

@@ -109,7 +109,7 @@ export default function VideoInfoCard({
       <PopoverSurface
         popover={pop}
         ariaLabel={t("card.info")}
-        className="glass w-[340px] max-w-[92vw] overflow-y-auto rounded-lg px-3.5 py-3 animate-[fadeIn_0.12s_ease]"
+        className="glass w-85 max-w-[92vw] overflow-y-auto rounded-lg px-3.5 py-3 animate-[fadeIn_0.12s_ease]"
         style={{ maxHeight: "min(26rem, var(--fit-max-h, 26rem))" }}
       >
         <p className="text-sm font-medium leading-snug wrap-break-word">{video.title}</p>