feat(sw): viewer layer bulb, popup toggle switch, footer layout and 1440px story inner

- SW Viewer layer popup: search + 전체 레이어 fixed, only the list scrolls; the all-layers
  control is the SWLayerVisibilityIcon bulb (role="switch"), one light #d2c8b4 line under it.
- Example H and the layer popup AI docs follow the bulb layout (VIEWER, DESIGN_RULES,
  COMPONENT_CATALOG, COMPOSITION_PATTERNS, AI_GUIDE sync).
- Popup toggle switch (Figma toggle_btn_new 633:75188 / 633:75902): one sw.css face for the
  HM UI Switch in SWPopup and SWViewerSwitch in SWViewerPanel; SW Header switches unchanged.
- SW Footer stories: no inner scrollers, fluid screens; workspace fits the viewport.
- SW Footer category tabs keep their positions when selected (divider slots kept, pocket
  edges drawn over the neighbours' padding).
- Storybook .sb-page-inner: 1440px max from 1920px (was 80vw).
- SW Header equal-split change was cancelled; header CSS unchanged.

Verified: check:ai-docs PASS, viewer test 49 PASS (1 FAIL hover face + timeout pre-existing),
footer-design-review 21 PASS, browser checks of switch/footer/inner.
Not verified: footer-popup-viewer-refinement (needs full Storybook build), text-weight/hover
tests, Switch 37x16 AI docs (deferred).

src/components/story-page.css

@@ -18,10 +18,10 @@
   min-width: 0;
   margin-inline: auto;
 }
-/* Wide screens (2026-10-22): 80% of the viewport, i.e. 1536px at 1920px, growing beyond it (vw, so a scrollbar does not
-   shrink it). Below 1920px the rule above applies. */
+/* Wide screens (2026-10-22): 1440px from 1920px up, fixed beyond it (was 80vw); never wider than the page minus the
+   gutters, so no horizontal scroll. Below 1920px the rule above applies. */
 @media (min-width: 1920px) {
-  .sb-page > .sb-page-inner { width: 80vw; }
+  .sb-page > .sb-page-inner { width: min(1440px, calc(100% - 2 * var(--sb-page-gutter))); }
 }
 
 .sb-page .sb-page-header {