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>

tests/global-topbar-contract.test.js

@@ -148,3 +148,35 @@ assertExcludes(
 	'brand-header',
 	'Removed brand banner widget area should not remain registered'
 );
+
+const unreadDrawer = read('templates/partials/header/unread-drawer.tpl');
+assertIncludes(
+	topbar,
+	'<!-- IMPORT partials/header/unread-drawer.tpl -->',
+	'Topbar should mount the unread drawer before notifications'
+);
+assert(
+	topbar.indexOf('partials/header/unread-drawer.tpl') < topbar.indexOf('partials/sidebar/notifications.tpl'),
+	'Unread drawer should sit before the notifications item'
+);
+assertIncludes(
+	unreadDrawer,
+	'component="unread/count"',
+	'Unread toggle should carry the live core count badge'
+);
+assertIncludes(
+	unreadDrawer,
+	'data-wg-unread-menu',
+	'Unread dropdown menu should expose the JS mount hook'
+);
+assertMatches(
+	topbar,
+	/href="\{relative_path\}\/unread"[^>]*>[\s\S]*?component="unread\/count"/,
+	'Mobile drawer actions should include an Unread link with count badge'
+);
+
+assertIncludes(
+	stylesheet,
+	'.unread-dropdown',
+	'Topbar styles should cover the unread dropdown'
+);