bootstrap SAM stack — S3 bucket + stub Lambda

functions/sign_pdfs/requirements.txt

@@ -1,6 +1,3 @@
-# Deps for the sign_pdfs lambda. Bundled into its deployment zip when
-# uploading to AWS; locally, the runner pod installs the union of all
-# per-function requirements (see Dockerfile.lambda).
-aioboto3>=15.0    # async S3 client used in handler.py
+# Same deps as sign_pdfs/ — this is the "after" demo fork, same dep footprint.
+aioboto3>=15.0    # async S3 client
 aiofiles>=23.2    # async file I/O for the JSONL manifest in /tmp
-boto3>=1.40       # sync S3 client used by seed.py (data setup utility)