data: add Azion Scale Up credit program

[J36-Ai-Editer]

What changed

Adds Azion as one new vendor with one startup-specific offer: up to USD 120,000 in promotional service credits through the Azion Scale Up Credit Program.

The contribution is data-only and changes exactly one file: vendors/az/azion.yaml.

First-party sources

• https://www.azion.com/en/lp/azion-scale-up/
• https://www.azion.com/en/documentation/agreements/azion-incentive-credits-terms-and-conditions/

Validation

• Pinned Sourcey Catalog Verifier: {"status":"valid","vendors":1,"programs":1,"offers":1}
• DCO sign-off included
• Duplicate check completed across current main and open/closed issues and pull requests

Closes #752

Certification

• I changed only allowed repository content and did not mix vendor YAML with other paths.
• Public sources substantiate every submitted factual value; Sourcey-written prose is a neutral summary.
• I did not author verification, provenance, freshness, or signature claims.
• My commit includes a Signed-off-by line.