feat(frontend): main menu lists accounts with their avatars, switching opens the last chat of that account

frontend/src/lib/components/ui/Avatar.svelte

@@ -3,7 +3,7 @@
   import { initials as toInitials } from "#lib/format/peer.js";
 
   interface Props {
-    avatar?: { kind: AvatarKind; id: number } | null;
+    avatar?: { account?: number; kind: AvatarKind; id: number } | null;
     colorKey?: number;
     deleted?: boolean;
     hasAvatar?: boolean;
@@ -41,7 +41,7 @@
       return;
     }
     let active = true;
-    loadAvatar(avatar.kind, avatar.id).then((resolved) => {
+    loadAvatar(avatar.kind, avatar.id, avatar.account).then((resolved) => {
       if (active) {
         url = resolved;
       }