Add Celo Camp Batch 5 builder lessons article

[jynbil1]

Submission for #5.

Adds an original blog post: "Celo Camp Batch 5: What Builders Can Still Learn From a Real-World Web3 Cohort".

Angle:

• Treats Batch 5 as a practical product/market map for Celo builders.
• Covers ReFi, payments/remittances, creator/community products, and developer tooling.
• Uses public sources and includes a source list at the end.

Happy to revise the title, length, publishing format, or angle if selected.

[vercel]

@jynbil1 is attempting to deploy a commit to the Kontext Team on Vercel.

A member of the Team first needs to authorize it.