feat: add alsoKnownAs field to federation settings

thoughts-frontend/components/federation/migration-settings.tsx

@@ -0,0 +1,57 @@
+"use client";
+
+import { useState } from "react";
+import { setAlsoKnownAs } from "@/lib/api";
+import { useAuth } from "@/hooks/use-auth";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { toast } from "sonner";
+
+export function MigrationSettings() {
+  const { token } = useAuth();
+  const [value, setValue] = useState("");
+  const [saving, setSaving] = useState(false);
+
+  const handleSave = async () => {
+    if (!token) return;
+    setSaving(true);
+    try {
+      await setAlsoKnownAs(value.trim() || null, token);
+      toast.success(value.trim() ? "Also known as saved." : "Also known as cleared.");
+    } catch {
+      toast.error("Failed to save.");
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  return (
+    <div className="glass-effect glossy-effect bottom rounded-md shadow-fa-lg p-4 space-y-3">
+      <div>
+        <h3 className="text-lg font-medium">Account migration</h3>
+        <p className="text-sm text-muted-foreground">
+          Set your new actor URL before broadcasting a Move. This lets remote
+          servers verify the migration is legitimate.
+        </p>
+      </div>
+      <div className="space-y-1">
+        <label className="text-sm font-medium">Also known as</label>
+        <p className="text-xs text-muted-foreground">
+          The full actor URL on your new server, e.g.{" "}
+          <code className="font-mono">https://newdomain.com/users/&lt;uuid&gt;</code>
+        </p>
+        <div className="flex gap-2">
+          <Input
+            value={value}
+            onChange={(e) => setValue(e.target.value)}
+            placeholder="https://newdomain.com/users/…"
+            className="font-mono text-sm"
+          />
+          <Button onClick={handleSave} disabled={saving} size="sm">
+            {saving ? "Saving…" : "Save"}
+          </Button>
+        </div>
+      </div>
+    </div>
+  );
+}