Feat v0.7.0 shell contract + surface audit + rebrand

Two-slot shell topbar (home, left, center, bell, user menu) with SDK API
(setLeft/setSlot/setTitle/hide/show). All 4 primary surfaces migrated:
Settings and Team Admin to Pattern B (flat tabs), Admin to Pattern C
(category tabs + sidebar), Docs to Pattern A (default).

Backend WS events: package.changed (broadcast), auth.changed (targeted),
notification.all_read. User menu re-fetches on package/auth changes.
Bell syncs read state across tabs.

Error handling pass with .sw-inline-error CSS primitive. Empty state
guidance for Admin Workflows/Groups. Announcement global dismiss via
localStorage. Rebrand assets deployed (both b/e icon variants, wordmarks,
full icon library). Docs outline scroll-to-heading fix.

Bug fixes: ICD security assertion tightened, workflow-demo error surfacing,
signoff display names, hello-dashboard + team-admin/groups.js deleted.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/pages/templates/surfaces/extension.html

@@ -13,6 +13,7 @@
 {{define "surface-extension"}}
 <div id="extension-surface" class="extension-surface"
      data-surface-id="{{.Surface}}">
+    <div id="shell-topbar"></div>
     <div id="extension-mount" class="extension-mount" data-ext="{{.Surface}}"></div>
 </div>
 {{end}}