feat: add post confirmation lambda hook

signup-lambda/src/main.rs

@@ -0,0 +1,11 @@
+use lambda_runtime::{run, service_fn, tracing, Error};
+mod handler;
+
+use handler::handler as function_handler;
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    tracing::init_default_subscriber();
+
+    run(service_fn(function_handler)).await
+}