data: add SendPulse startup grant

[Validragon4]

Closes #676

What changed

Added SendPulse and its public Startup Grant to the catalog. The record covers the $5,000 credit amount, one-year duration, tool exclusions, all four published eligibility criteria, and the public application route.

The repository's pinned official validator reports valid with exactly 1 vendor, 0 programs, and 1 offer.

Source

• https://sendpulse.com/startup

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 commit includes a Signed-off-by line.