fix: resolve federated avatar color to home instance identity

Federated users get a different snowflake ID on remote instances,
causing avatar gradients to mismatch their home identity. Apply
resolveDisplayIdentity/isSelf resolution in VoiceUser, StreamTile,
VoiceChannel sidebar, and MemberSidebar so the current user's avatar
color is consistent across all views.

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

@@ -1,6 +1,7 @@
 import React, { useRef, useEffect, useState, useCallback } from 'react';
 import { Avatar } from '../ui/Avatar';
 import { useVoiceStore } from '../../stores/voiceStore';
+import { useAuthStore } from '../../stores/authStore';
 import type { UserTile } from '../../hooks/useLiveKit';
 
 interface VoiceUserProps {
@@ -20,6 +21,8 @@ export function VoiceUser({ tile, large }: VoiceUserProps) {
 
   const perUserVolume = participantVolumes.get(participant.userId) ?? 100;
   const isLocal = participant.isLocal;
+  const homeUser = useAuthStore((s) => s.user);
+  const avatarUserId = isLocal ? (homeUser?.id ?? participant.userId) : participant.userId;
 
   // --- VIDEO & UI ---
 
@@ -95,7 +98,7 @@ export function VoiceUser({ tile, large }: VoiceUserProps) {
               src={null}
               name={participant.username}
               size={large ? 100 : 64}
-              userId={participant.userId}
+              userId={avatarUserId}
             />
             {isSpeaking && (
               <div className="absolute -inset-1.5 rounded-full ring-[3px] ring-status-online animate-pulse" />