Add argon2 polyfill and unified preview/API startup for admin login.

Node < 24 lacks crypto.argon2Sync; wire @node-rs/argon2 fallback and start Admin API alongside vite preview in local and remote deploy flows.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/index.mjs

@@ -1,4 +1,7 @@
+import { ensureArgon2Sync } from './argon2-polyfill.mjs';
 import { loadProjectEnv } from './load-env.mjs';
+
+ensureArgon2Sync();
 import { bootstrapAdminServices } from './bootstrap.mjs';
 import { importMemind } from './lib-path.mjs';
 import { createAdminApp } from './app.mjs';