docs: refresh README images and status badges

[ernestoongaro]

Problem

The README logo points to an unavailable GitHub attachment, the DAG screenshot shows the older docs UI, and the CI badge tracks the retired Python workflow.

Solution

• Store the logo and a dbt 2.0 DAG screenshot in assets/ and use relative links.
• Display the logo at 400px and crop the DAG side margins for readability. The DAG was generated with dbt 2.0.5 and DuckDB: three sources feed three staging views, then fct_orders and an Omni dashboard exposure.
• Point CI at the current upstream Rust workflow on main, and add release and Apache 2.0 license badges.

Validation

Verified the rendered README images, checked both new badge endpoints, and ran git diff --check. The example's four models built successfully in DuckDB. No runtime code changed; automated tests are not relevant.

Checklist

• I have read the contributing guide and understand what's expected of me.
• I have run this code in development, and it appears to resolve the stated issue.
• This PR includes tests, or tests are not required or relevant for this PR.
• This PR has no interface changes.

No changelog entry is included for this README-only update; a maintainer can apply Skip Changelog.

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.