llm: auto-load active config from arcadia on app boot

Adds <LlmConfigBootstrap /> in root.tsx that, when localStorage has no
active LLM settings, fetches enabled configurations from arcadia and
seeds the active settings (provider/model/baseURL/secretName + reasoning
effort) from the preferred row. Idempotent and silent on auth failure;
retries on session change.

Selection: prefer metadata.default === true, otherwise first enabled row.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/root.tsx

@@ -13,6 +13,7 @@ import "./app.css"
 import { ToastProvider, Toaster } from "@crema/notification-ui"
 import { CommandBusProvider } from "@crema/action-bus"
 import { ArcadiaProvider } from "@crema/arcadia-client"
+import { LlmConfigBootstrap } from "~/lib/llm-config-bootstrap"
 // CREMA:PROVIDERS-IMPORTS
 
 const ARCADIA_URL = import.meta.env.VITE_ARCADIA_URL ?? "http://localhost:4000"
@@ -61,6 +62,7 @@ export default function App() {
         }}
       >
         <CommandBusProvider>
+          <LlmConfigBootstrap />
           <Outlet />
           <Toaster />
         </CommandBusProvider>