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/widgets/mascot/MascotImage.tsx

@@ -70,7 +70,7 @@ export function MascotImage({
         >
           <div className="relative">
             {/* Chat bubble */}
-            <div className="bg-gradient-to-br from-primary/90 to-primary/80 text-white rounded-2xl px-4 py-2.5 shadow-lg backdrop-blur-sm border border-primary/50">
+            <div className="bg-primary/90 text-primary-foreground rounded-xl px-4 py-2.5 shadow-lg backdrop-blur-sm border border-primary/30">
               <div className="flex items-start gap-2">
                 <MessageCircle className="h-4 w-4 shrink-0 mt-0.5 text-white/80" />
                 <p className="text-xs leading-relaxed font-medium line-clamp-3">