Glassmorphism polish: frosted pills + glass sidebar nav states

Neutral badges become frosted (translucent + blur), the primary badge picks up the
gradient, and the sidebar nav active/hover states are now a frosted white highlight
(ring + blur) instead of the opaque accent — cohesive on the dark-glass sidebar.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/src/components/AppShell.tsx

@@ -96,9 +96,11 @@ function NavItem({
   const active = to ? location.pathname === to : false
 
   const className = cn(
-    'flex items-center gap-3 rounded-md px-3 py-2 text-sm',
-    active ? 'bg-sidebar-accent font-medium text-sidebar-accent-foreground' : 'text-sidebar-foreground/80',
-    muted ? 'opacity-50' : 'hover:bg-sidebar-accent/60',
+    'flex items-center gap-3 rounded-lg px-3 py-2 text-sm transition-colors',
+    active
+      ? 'bg-white/15 font-medium text-white shadow-sm ring-1 ring-white/15 backdrop-blur-sm'
+      : 'text-sidebar-foreground/80',
+    muted ? 'opacity-50' : 'hover:bg-white/10 hover:text-white',
   )
 
   const content = (