feat: add Whop integration

[pranavrajs]

Adds the Whop integration (Commerce). Look up customers, memberships, payments, products, and pricing in a Whop business.

Tools

• Find Customer by Email (find_customer_by_email, GET)
• List Memberships (list_memberships, GET)
• Get Membership (get_membership, GET)
• List Payments (list_payments, GET)
• Get Payment (get_payment, GET)
• Get Product (get_product, GET)
• Get Plan (get_plan, GET)

Testing

• The manifest passes the validator ("valid": true).
• Every template was rendered locally with Liquid 5.4.0 against sample responses built from Whop's API docs.
• Not run against the live API. No credentials were available, so tool-tester.rb has not been run with a real key. This needs doing before merge.
• No logo is included.

Review notes

• Whop's current API reference is date-versioned and under a beta path; no Api-Version-Date is pinned, so response shapes may drift.
• The permission names in the README were taken from the spec text, not confirmed per endpoint.
• License keys, client secrets and recovery URLs are left out of the output.

The root README.md row and .env.example entry for this integration are in a separate PR, so the per-integration PRs do not conflict with each other.

[pranavrajs]

Closing: no new integrations are being added in this round. The branch is kept in case this is wanted later.