Hi! Just reading the docs, this looks really slick. I had a few questions:

- When you create tables, are they always connected to a source? How does that work for the cloud version (ie, source = filesystem? would we just use s3, it seems.) - Does arroyo poll an s3 bucket for new files and automatically ingest? - Are you able to do ALTER TABLE? (What if data, or data types, are mismatched?) - Similarly, am I able to change the primary key (ie, clickhouse's ORDER BY or projections?) or change indexes?

Any plans for HTTP as a source? (This is what we build and I'd be happy to prototype an integration!)