Add Sharpe API

[rishabhng]

Adds Sharpe to the Bitcoin/Bitcoin Wallets API category.

The category already includes market and exchange data APIs such as Bitcoincharts and Exchange Rates API. Sharpe fits as a crypto market intelligence API for funding rates, derivatives, arbitrage, narratives, listings, and news.

Website URL: https://www.sharpe.ai/docs/free-api
Validation: git diff --check passes.
Linear: SHA-204

Disclosure: I work on Sharpe.

[rishabhng]

Following up on this API listing. The intent is to add Sharpe as a crypto market data and intelligence API, not as a general app listing.

I kept it to one row and linked the API docs directly. If the repo prefers shorter descriptions or a different category label, I can revise the entry.