feat: unified glass material system for all floating surfaces

Add .glass-modal CSS class (0.82 opacity) for dialogs and apply
consistent glass tiers across all floating UI: modals, context menus,
tooltips, popovers, and call cards. Replaces ad-hoc bg-surface-elevated
and inline styles with the documented 5-tier glass hierarchy.

packages/web/src/components/ui/ContextMenu.tsx

@@ -64,7 +64,7 @@ export function ContextMenu({ items, children }: ContextMenuProps) {
       {isOpen && (
         <div
           ref={menuRef}
-          className="fixed z-[200] min-w-[180px] py-1.5 bg-surface-elevated rounded-md shadow-elevation-high animate-fade-in max-h-[calc(100vh-16px)] overflow-y-auto scrollbar-thin"
+          className="fixed z-[200] min-w-[180px] py-1.5 glass rounded-md animate-fade-in max-h-[calc(100vh-16px)] overflow-y-auto scrollbar-thin"
           style={{ left: position.x, top: position.y }}
         >
           {items.map((item, i) => (