p2 layout

- _tokens.scss — added --wg-space-2xs…xl (0.25–2rem, 4pt scale), --wg-ledger-line: 1.78rem, --wg-page-width: 1420px.
- Card gaps unified to --wg-space-sm, card interiors to --wg-space-md, the compact topic-list header to --wg-space-xs (_categories.scss, _topics.scss, _widgets.scss, _responsive.scss).
- Ledger ruling height is now one token across topics, posts, pagination, quick-reply, and the composer (_posts.scss, _controls.scss).
- Footer rails now share the topbar's 1420px measure (_footer.scss:36,123,143), so the page's top and bottom edges align.
- Stat tiles got explicit padding instead of inheriting Bootstrap's (_topics.scss:369, _categories.scss:326).
- Documented the scale and rules in DESIGN.md (new "Spacing & Layout" section).

scss/westgate/_controls.scss

@@ -399,7 +399,7 @@ table[component="notification/table"] a[data-type]:focus {
     ),
     linear-gradient(100deg, rgba(32, 19, 30, 0.98), rgba(13, 12, 17, 0.98)) !important;
   background-size:
-    100% 1.82rem,
+    100% var(--wg-ledger-line),
     auto;
   border-color: rgba(194, 163, 90, 0.18) !important;
   color: var(--wg-text-soft) !important;