feat: stateless federated identity resolver + federation UX improvements

Add identity.ts with isSelf() and resolveDisplayIdentity() — pure
stateless functions that detect replicated-self using the immutable
(username, homeInstance) composite key. No store lookups, no data
mutation. Fixes wrong avatar gradient and missing edit/delete on
own messages in remote channels.

Also includes: optimistic message dedup fix for cross-instance
messages (content-only matching), federation toast notifications,
Username component with @domain display, invite parser, and
deploy script simplification.

packages/web/src/hooks/useFederationToasts.ts

@@ -0,0 +1,47 @@
+import { useEffect, useRef } from 'react';
+import { useInstanceStore, type ConnectedInstance } from '../stores/instanceStore';
+import { useUIStore } from '../stores/uiStore';
+
+/**
+ * Watches instanceStore for status changes on remote instances and fires
+ * toast notifications when connections are lost or restored.
+ */
+export function useFederationToasts() {
+  const instances = useInstanceStore((s) => s.instances);
+  const addToast = useUIStore((s) => s.addToast);
+  const prevStatuses = useRef<Map<string, ConnectedInstance['status']>>(new Map());
+
+  useEffect(() => {
+    const prev = prevStatuses.current;
+
+    for (const inst of instances) {
+      const prevStatus = prev.get(inst.origin);
+      if (prevStatus === undefined) {
+        // First time seeing this instance — record but don't toast
+        continue;
+      }
+      if (prevStatus === inst.status) continue;
+
+      const label = inst.label || (() => { try { return new URL(inst.origin).host; } catch { return inst.origin; } })();
+
+      if (
+        prevStatus === 'connected' &&
+        (inst.status === 'disconnected' || inst.status === 'error')
+      ) {
+        addToast(`Lost connection to ${label} — reconnecting...`, 'warning');
+      } else if (
+        (prevStatus === 'disconnected' || prevStatus === 'error' || prevStatus === 'connecting') &&
+        inst.status === 'connected'
+      ) {
+        addToast(`Reconnected to ${label}`, 'success');
+      }
+    }
+
+    // Update prev statuses
+    const next = new Map<string, ConnectedInstance['status']>();
+    for (const inst of instances) {
+      next.set(inst.origin, inst.status);
+    }
+    prevStatuses.current = next;
+  }, [instances, addToast]);
+}

packages/web/src/hooks/useWebSocket.ts

@@ -107,6 +107,13 @@ function handleEvent(origin: string, event: ServerEvent): void {
 
       populateFromReady(origin, event.servers, event.folders, event.dmChannels);
 
+      // Mark remote instance as connected in instanceStore
+      if (!isHome) {
+        import('../stores/instanceStore').then(({ useInstanceStore }) => {
+          useInstanceStore.getState().setInstanceStatus(origin, 'connected');
+        });
+      }
+
       if (isHome && currentServerId) {
         loadServerDetail(currentServerId);
       }
@@ -518,6 +525,12 @@ function connectToOrigin(origin: string, token: string): void {
   ws.onclose = () => {
     conn.ws = null;
     stopHeartbeat(conn);
+    // Mark remote instance as disconnected in instanceStore
+    if (origin !== HOME_ORIGIN) {
+      import('../stores/instanceStore').then(({ useInstanceStore }) => {
+        useInstanceStore.getState().setInstanceStatus(origin, 'disconnected', 'Connection lost — reconnecting');
+      });
+    }
     // Only reconnect if the connection is still registered (not explicitly disconnected)
     if (connections.has(origin) && conn.token) {
       const delay = Math.min(1000 * Math.pow(2, conn.reconnectAttempts), 30000);