feat: Aether Drift UI polish — popout redesign, sidebar cleanup, status dot fix

- Redesign UserProfilePopout with glass material, viewport clamping, flow-based
  avatar layout, and subtle send-message button
- Server sidebar: downsize icons to 40px (matching prototype), remove nonfunctional
  Explore button, add separator before action buttons, replace Tooltip with native
  title, remove hover boxShadow artifacts
- Avatar status dot: fixed 12px size with semi-transparent border for universal
  cutout effect matching the design prototype
- MemberListToggleButton: distinct three-person icon (was duplicate of Add Friends)
- FriendsPage: fix Add Friend button contrast (dark text on mint background)
- ChannelSidebar: rename Nitro/Shop to Coming Soon placeholders

packages/web/src/components/chat/FriendsPage.tsx

@@ -197,7 +197,7 @@ export function FriendsPage() {
           <button
             onClick={() => setActiveTab('add')}
             className={`px-2 py-0.5 rounded text-[14px] font-medium transition-all ${
-              activeTab === 'add' ? 'text-status-online bg-transparent' : 'bg-status-online text-white hover:bg-status-online/90'
+              activeTab === 'add' ? 'text-status-online bg-transparent' : 'bg-status-online text-[#13131a] hover:bg-status-online/90'
             }`}
           >
             Add Friend