Add IronCore Labs startup program

[shawnruan0218-code]

What changed

• Add the missing IronCore Labs vendor record.
• Capture the public two-year SaaS Shield or Cloaked Search Pro startup offer.
• Model the published eligibility and 100-tenant SaaS Shield limit.

Closes #614

Sources

• https://ironcorelabs.com/startup-program/

Validation

• Pinned Sourcey Catalog Verifier: {"status":"valid","vendors":1,"programs":1,"offers":1}

Certification

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

[shawnruan0218-code]

Hi @auscaster — PRs #615 through #619 are five independent, data-only vendor contributions. Each has green sourcey/validation, a DCO-signed commit, first-party source links, and the completed certification checklist. They are ready for Sourcey admission review when you reach this batch. Thank you.