feat: integrate Pi backend and Pi Web

pi-web/app/api/auth/logout/[provider]/route.ts

@@ -0,0 +1,18 @@
+import { ModelRuntime } from "@earendil-works/pi-coding-agent";
+import { invalidateModelsCache } from "@/lib/models-cache";
+
+export const dynamic = "force-dynamic";
+
+export async function POST(
+  _req: Request,
+  { params }: { params: Promise<{ provider: string }> }
+) {
+  const { provider } = await params;
+  const modelRuntime = await ModelRuntime.create();
+  if (!modelRuntime.getProvider(provider)?.auth.oauth) {
+    return Response.json({ error: `Unknown provider: ${provider}` }, { status: 400 });
+  }
+  await modelRuntime.logout(provider);
+  invalidateModelsCache();
+  return Response.json({ ok: true });
+}