Add The SaaSy People startup program

[kkmm6657]

What changed

• Add The SaaSy People as a new customer-support vendor.
• Add the SaaSy for Startups program with one offer: 50% off Startup Shared Agent outsourced customer support plans for up to 12 months.
• Model the published funding, company-age, employee-count, and existing-customer eligibility requirements.

Closes #640

Sources

• https://www.thesaasypeople.com/startups

Validation

• Pinned Sourcey Catalog Verifier: {"status":"valid","vendors":1,"programs":1,"offers":1}
• git diff --check origin/main...HEAD: passed

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.