feat(ui): overhaul frontend with IMPHNEN visual identity

- Update CSS foundation: HSL→oklch color tokens, Poppins font, new utilities
- Replace Three.js sakura particles with CSS glow orbs
- Rebrand Header with IMPHNEN logo and gradient text
- Update all UI components (Button, Card, Badge, Input, Select, Tabs, Toast)
- Apply IMPHNEN design patterns (glass, gradient, grid) to layout
- Remove all hardcoded #7EC8E3/#FFB7C5/#FCA5A5 references
- Standardize rounded-xl across all components
- Replace emoji toasts with Lucide icons

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

services/frontend/src/shared/ui/card.tsx

@@ -8,7 +8,7 @@ export function Card({
   return (
     <div
       className={cn(
-        "rounded-2xl border border-border bg-white text-card-foreground shadow-md hover:shadow-lg transition-shadow",
+        "rounded-xl border border-border bg-card text-card-foreground shadow-sm hover:shadow-md transition-shadow",
         className,
       )}
       {...props}