Topbar unread drawer (#28)

Adds an Unread dropdown to the topbar utilities (before notifications), per docs/superpowers/plans/2026-07-17-topbar-unread-drawer.md.

- New partial `templates/partials/header/unread-drawer.tpl`: toggle with live `component="unread/count"` badge (core socket updates), server-rendered empty/footer rows.
- `public/client.js`: on dropdown open, fetches `GET /api/unread` and injects up to 10 topic rows (titles/categories via textContent only); fetch failure falls back to the empty state.
- Mobile burger drawer gets an Unread row with the same badge.
- SCSS: unread dropdown joins the shared dropdown width rule; flex row styles for topic items.

Deviations from the plan's example code, found by live verification against the dev forum:
- Plan's `api.get('/unread')` hits the v3 write API and 404s → replaced with a fetch of the `/api/unread` read route.
- NodeBB 4 has no global `window.require`, so runtime translation of the static `[[unread:...]]` strings never ran → those strings are now server-rendered in the template (also removes the plan's translate-over-innerHTML step, which would have re-parsed untrusted titles as HTML).

Verified: full plain-node test suite passes; Playwright against the dev container passed all checks (badge count, item ordering before notifications, dropdown topic links + navigation, /unread footer link, mobile drawer badge at 390px).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #28
Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Co-committed-by: vickydotbat <vickydotbat@tutamail.com>

scss/westgate/_topbar.scss

@@ -172,10 +172,23 @@ $wg-topbar-panel-bg: rgba(21, 17, 26, 0.98);
 
 .wg-topbar .notifications-dropdown,
 .wg-topbar .chats-dropdown,
-.wg-topbar .drafts-dropdown {
+.wg-topbar .drafts-dropdown,
+.wg-topbar .unread-dropdown {
   width: min(24rem, calc(100vw - 1.5rem));
 }
 
+.wg-topbar .wg-unread-item {
+  display: flex;
+  align-items: baseline;
+  gap: 0.5rem;
+}
+
+.wg-topbar .wg-unread-item__category {
+  margin-left: auto;
+  flex-shrink: 0;
+  opacity: 0.7;
+}
+
 .wg-topbar .dropdown-item,
 .wg-topbar .btn.btn-ghost,
 .wg-topbar .btn.btn-light {