data: add GetBlock Solana grant program

[thiago-ss]

What changed

Adds GetBlock as a new vendor with one offer: the Solana Grant Program. Approved Solana teams can receive up to $10,000 in non-cash compute credits applied to their GetBlock account, with access lasting up to 90 days.

Sources

• https://getblock.io/grant-program-solana/
• https://getblock.io/terms-of-service/grant-program-solana/
• https://getblock.io/blog/getblock-opens-solana-startup-program/

Certification

• I changed only allowed repository content and did not mix Entity 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.

Closes #593