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/features/live/components/ActiveSpeakers.tsx

@@ -18,12 +18,12 @@ export function ActiveSpeakers({ speakers }: ActiveSpeakersProps) {
         return (
           <div
             key={key}
-            className="flex items-center gap-3 rounded-xl border border-sky-200 bg-white p-3"
+            className="flex items-center gap-3 rounded-xl border border-border bg-card p-3"
           >
             <img
               src={s.avatar}
               alt=""
-              className="h-8 w-8 rounded-full object-cover ring-2 ring-[#7EC8E3]/40"
+              className="h-8 w-8 rounded-full object-cover ring-2 ring-primary/30"
             />
             <div className="min-w-0">
               <div className="truncate text-sm font-medium">{s.username}</div>