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/button.tsx

@@ -11,17 +11,19 @@ type ButtonVariant =
 type ButtonSize = "default" | "sm" | "lg" | "icon";
 
 const variants: Record<ButtonVariant, string> = {
-  default: "bg-primary text-primary-foreground shadow hover:bg-primary/90",
-  secondary: "bg-[#FFB7C5] text-[#1a1a2e] hover:bg-[#FFB7C5]/80",
-  destructive: "bg-[#FCA5A5] text-[#1a1a2e] hover:bg-[#FCA5A5]/80",
-  outline: "border border-border bg-white hover:bg-primary-soft",
-  ghost: "hover:bg-primary-soft",
+  default: "bg-primary text-primary-foreground shadow-sm hover:bg-primary/90",
+  secondary: "bg-secondary text-secondary-foreground hover:bg-secondary/80",
+  destructive:
+    "bg-destructive text-destructive-foreground hover:bg-destructive/90",
+  outline:
+    "border border-input bg-background hover:bg-accent hover:text-accent-foreground",
+  ghost: "hover:bg-accent hover:text-accent-foreground",
 };
 
 const sizes: Record<ButtonSize, string> = {
   default: "h-10 px-4 py-2",
-  sm: "h-9 rounded-xl px-3",
-  lg: "h-11 rounded-xl px-8",
+  sm: "h-9 rounded-lg px-3",
+  lg: "h-11 rounded-lg px-8",
   icon: "h-10 w-10",
 };
 
@@ -43,7 +45,7 @@ export function Button({
   return (
     <Comp
       className={cn(
-        "inline-flex items-center justify-center gap-2 whitespace-nowrap rounded-xl text-sm font-medium transition-all focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring active:scale-[0.97] disabled:pointer-events-none disabled:opacity-50",
+        "inline-flex items-center justify-center gap-2 whitespace-nowrap rounded-lg text-sm font-medium transition-all duration-200 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring active:scale-[0.97] disabled:pointer-events-none disabled:opacity-50",
         variants[variant],
         sizes[size],
         className,