fix(redesign): portal IconGridSelect popup + snap navbar to mockup

Three issues addressed:

1. IconGridSelect popup was clipped/mispositioned because the .panel
   ancestor has backdrop-filter, which makes it the containing block
   for position:fixed descendants (CSS spec gotcha). Added a tiny
   portal action ($lib/portal) that re-parents the popup + backdrop
   to document.body, and refreshed the popup styling to be Aurora-
   native (solid surface, gradient active state, glass-strong search).

2. Always-visible top search bar: a sticky glass strip at the top of
   every page with the search trigger (⌘K), theme cycler, locale
   toggle, and a primary 'New tracker' gradient CTA — moved out of
   the sidebar to free up rail space and make search reachable from
   anywhere. The sidebar's inline search button is gone.

3. Navbar snapped to the mockup:
   - Sidebar footer redone as a glass user-card (avatar gradient +
     username + role + mint live chip + change-password / docs / logout
     row beneath a hairline).
   - Section labels above each nav group (Overview / Routing /
     Operators / System) with a hairline rule that extends to the
     edge — same rhythm as the dashboard mockup.
   - Active nav link keeps the gradient bar + glass-elev background
     + inset highlight + soft outer glow.

i18n: nav.section* keys (en + ru), dashboard.newTracker reused for
the topbar CTA. Build clean.

frontend/src/lib/i18n/ru.json

@@ -4,6 +4,10 @@
 		"tagline": "Уведомления о сервисах"
 	},
 	"nav": {
+		"sectionOverview": "Обзор",
+		"sectionRouting": "Маршрутизация",
+		"sectionOperators": "Операторы",
+		"sectionSystem": "Система",
 		"dashboard": "Главная",
 		"providers": "Провайдеры",
 		"notificationTrackers": "Трекеры увед.",