Chalice Cannot Publish Layer Larger than 50MB, but the Limit is 250MB.

with ``"automatic_layer": true`` enabled in ``config.json`` chalice will zip all dependencies to a .zip file and directly call public_layer_version api. seems like chalice's default behavior is to upload .zip file directly.

I think the recommended way is to upload the .zip layer file to S3 and then publish the new layer version from S3. Because direct upload has 50MB limit but deploy from S3 can use 250MB.

My suggestion:

1. package locally, and calculate md5 finger print.
2. comparing local md5 with s3 object md5, if they are the same, don't upload and publish new version
3. otherwise, upload, and publich

Start by tracing the automatic_layer path enabled through config.json and the direct public_layer_version API call. Check how the .zip package is fingerprinted and uploaded, then verify the S3-based publish flow skips upload and new-version publication when the local and S3 MD5 values match, while supporting layers up to the stated 250MB limit.

Written by the indexing model from the issue text.