feat: normalize remote asset URLs and route UI actions by instance origin

Phase 5 of multi-instance federation. Adds a two-layer fix:

Layer 1 — Data ingestion normalization: Remote instance user avatars,
server icons, and attachment filenames are rewritten to absolute URLs
when entering the app (via WebSocket events or API responses), so all
downstream components render them correctly without changes.

Layer 2 — Outbound action routing: wsSend calls (voice join/leave/status,
typing) and file uploads in UI components now route through the correct
instance based on the active channel's origin.

packages/web/src/hooks/useWebSocket.ts

@@ -6,6 +6,7 @@ import { useVoiceStore } from '../stores/voiceStore';
 import { useSocialStore } from '../stores/socialStore';
 import { useSettingsStore } from '../stores/settingsStore';
 import type { ServerEvent, ClientEvent, ActiveCallInfo } from '@backspace/shared';
+import { resolveAssetUrl, normalizeUserAssets, normalizeMessageAssets } from '../utils/assetUrls';
 
 // ─── Connection state ─────────────────────────────────────────────────────────
 
@@ -92,6 +93,18 @@ function handleEvent(origin: string, event: ServerEvent): void {
         useSettingsStore.getState().fetchStreamingLimits();
       }
 
+      // Normalize asset URLs for remote origins before dispatching to stores
+      if (!isHome) {
+        for (const server of event.servers) {
+          if (server.icon) server.icon = resolveAssetUrl(server.icon, origin) ?? server.icon;
+          if ((server as any).members) {
+            for (const member of (server as any).members) {
+              if (member.user) normalizeUserAssets(member.user, origin);
+            }
+          }
+        }
+      }
+
       populateFromReady(origin, event.servers, event.folders, event.dmChannels);
 
       if (isHome && currentServerId) {
@@ -169,6 +182,7 @@ function handleEvent(origin: string, event: ServerEvent): void {
       break;
 
     case 'message_created':
+      if (!isHome) normalizeMessageAssets(event.message, origin);
       addRealtimeMessage(event.message.channelId, event.message);
       {
         const { currentChannelId, markChannelUnread } = useChatStore.getState();
@@ -179,6 +193,7 @@ function handleEvent(origin: string, event: ServerEvent): void {
       break;
 
     case 'message_updated':
+      if (!isHome) normalizeMessageAssets(event.message, origin);
       updateMessage(event.message);
       break;
 
@@ -210,6 +225,7 @@ function handleEvent(origin: string, event: ServerEvent): void {
       break;
 
     case 'member_joined':
+      if (!isHome) normalizeUserAssets(event.member.user, origin);
       addMember(event.member);
       break;
 
@@ -435,6 +451,9 @@ function handleEvent(origin: string, event: ServerEvent): void {
     }
 
     case 'server_updated': {
+      if (!isHome && event.server.icon) {
+        event.server.icon = resolveAssetUrl(event.server.icon, origin) ?? event.server.icon;
+      }
       const { servers: currentServers, setServers } = useServerStore.getState();
       setServers(currentServers.map(s => s.id === event.server.id ? { ...s, ...event.server } : s));
       break;