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>

templates/partials/header/topbar.tpl

@@ -37,6 +37,10 @@
 				</li>
 				{{{ end }}}
 
+				<li component="unread" class="nav-item unread dropdown" title="[[unread:title]]">
+					<!-- IMPORT partials/header/unread-drawer.tpl -->
+				</li>
+
 				<li component="notifications" class="nav-item notifications dropdown" title="[[global:header.notifications]]">
 					<!-- IMPORT partials/sidebar/notifications.tpl -->
 				</li>
@@ -109,6 +113,7 @@
 
 			{{{ if config.loggedIn }}}
 			<div class="wg-topbar__drawer-actions">
+				<a href="{relative_path}/unread"><i class="fa fa-fw fa-inbox" aria-hidden="true"></i><span>[[unread:title]]</span><span component="unread/count" class="badge rounded-1 bg-primary {{{ if !unreadCount.topic }}}hidden{{{ end }}}">{unreadCount.topic}</span></a>
 				<a href="{relative_path}/notifications"><i class="fa fa-fw fa-bell" aria-hidden="true"></i><span>[[global:header.notifications]]</span><span component="notifications/count" class="badge rounded-1 bg-primary {{{ if !unreadCount.notification }}}hidden{{{ end }}}">{unreadCount.notification}</span></a>
 				{{{ if canChat }}}
 				<a href="{relative_path}/user/{user.userslug}/chats{{{ if user.lastRoomId }}}/{user.lastRoomId}{{{ end }}}"><i class="fa fa-fw fa-comment" aria-hidden="true"></i><span>[[global:header.chats]]</span><span component="chat/count" class="badge rounded-1 bg-primary {{{ if !unreadCount.chat }}}hidden{{{ end }}}">{unreadCount.chat}</span></a>