feat(admin): add-node form + After Effects version dropdown

- Nodes page: "+ افزودن نود" opens a full-screen form (name, region, IP, worker
  port, AE version, node kind, RAM, CPU, priority) → POST /v1/nodes
- current_ae_version is now a dropdown (2025…2020, matching the ae_version DB
  enum) instead of free text; node_kind is a dropdown (Shared/Dedicated/Spot)
- new POST /api/admin/nodes proxy route (forwards body; admin-gated). The backend
  POST /v1/nodes existed but had no UI — you couldn't define nodes before.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/api/admin/nodes/route.ts

@@ -0,0 +1,32 @@
+import { type NextRequest, NextResponse } from "next/server";
+import { gatewayUrl } from "@/lib/api/gateway";
+import { getAccessToken } from "@/lib/auth/session";
+import { decodeJwt } from "@/lib/auth/jwt";
+
+export const runtime = "nodejs";
+
+/** Create a render node (POST body forwarded to the gateway). Admin-gated. */
+export async function POST(req: NextRequest) {
+  const token = await getAccessToken();
+  if (!token) return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  const claims = decodeJwt(token);
+  const isAdmin =
+    String(claims?.is_admin) === "true" || claims?.is_admin === true || String(claims?.is_tenant_admin) === "true";
+  if (!isAdmin) return NextResponse.json({ error: "Forbidden" }, { status: 403 });
+
+  const body = await req.text();
+  const res = await fetch(gatewayUrl("/v1/nodes"), {
+    method: "POST",
+    cache: "no-store",
+    headers: { "Content-Type": "application/json", Authorization: `Bearer ${token}` },
+    body,
+  });
+  const data = await res.json().catch(() => null);
+  if (!res.ok) {
+    return NextResponse.json(
+      { error: data?.message ?? data?.error?.message ?? "Gateway error" },
+      { status: res.status }
+    );
+  }
+  return NextResponse.json(data ?? { ok: true });
+}