Add runtime configuration loader and styles for web application

public/web/runtime-config.js

@@ -0,0 +1,15 @@
+import { startNodewardenApp } from './app.js';
+
+async function loadRuntimeConfig() {
+  try {
+    const resp = await fetch('/api/web/config', { method: 'GET' });
+    if (!resp.ok) throw new Error('runtime config request failed');
+    return await resp.json();
+  } catch {
+    return { defaultKdfIterations: 600000 };
+  }
+}
+
+const cfg = await loadRuntimeConfig();
+startNodewardenApp(cfg || { defaultKdfIterations: 600000 });
+