fix: perfect speaking ring circle and use real avatars/display names in voice tiles

Add flex to speaking ring wrapper divs in VoiceUser and PictureInPicture
to eliminate baseline descender space that made the ring oval. Extract
useVoiceParticipantMeta hook to resolve real display names and avatars
for voice participants instead of showing raw usernames with null avatars.

packages/web/src/components/voice/VoiceUser.tsx

@@ -3,6 +3,7 @@ import { Avatar } from '../ui/Avatar';
 import { useVoiceStore } from '../../stores/voiceStore';
 import { VoiceUserContextMenu } from './VoiceUserContextMenu';
 import { useSpaceStore } from '../../stores/spaceStore';
+import { useVoiceParticipantMeta } from '../../hooks/useVoiceParticipantMeta';
 import type { UserTile } from '../../hooks/useLiveKit';
 
 interface VoiceUserProps {
@@ -28,6 +29,7 @@ export function VoiceUser({ tile, large }: VoiceUserProps) {
 
   const isLocal = participant.isLocal;
   const avatarUserId = participant.homeUserId ?? participant.userId;
+  const { displayName, avatar } = useVoiceParticipantMeta(participant);
 
   // --- VIDEO & UI ---
 
@@ -90,10 +92,10 @@ export function VoiceUser({ tile, large }: VoiceUserProps) {
         />
       ) : (
         <div className="w-full h-full flex flex-col items-center justify-center gap-3 bg-surface-channel">
-          <div className="relative">
+          <div className="relative flex">
             <Avatar
-              src={null}
-              name={participant.username}
+              src={avatar}
+              name={displayName}
               size={large ? 100 : 64}
               userId={avatarUserId}
             />
@@ -110,7 +112,7 @@ export function VoiceUser({ tile, large }: VoiceUserProps) {
             <span
               className={`font-semibold text-white truncate ${large ? 'text-base' : 'text-[13px]'}`}
             >
-              {participant.username}
+              {displayName}
             </span>
             {isLocal && (
               <span className="text-[10px] text-white/40 font-medium">