add per-agent smoke tests (#100)

test/fixtures/basic.ts

@@ -0,0 +1,11 @@
+import type { Payload } from "../../external.ts";
+
+export default {
+  "~pullfrog": true,
+  agent: null,
+  prompt:
+    "List all files in the current directory, then create a file called dynamic-test.txt with the content 'This was loaded from a TypeScript file!', then delete it.",
+  event: {
+    trigger: "workflow_dispatch",
+  },
+} satisfies Payload;