CreatePremiumCharge/VerifyPremium now POST /payments/create and GET
/payments/:id against the CoinPay API (Bearer COINPAY_API_KEY, business_id =
AGENTBBS_COINPAY_MERCHANT_ID), so the droplet needs no coinpay CLI installed.
The created payment id is stored (store: User.PremiumPayID + premium_pay_id col
+ SetPremiumPayment); ensurePremium verifies that id on a later connect and
grants premium on confirmed/forwarded status. Removed the CLI command-template
env knobs; added AGENTBBS_COINPAY_API_URL. Tests: httptest-backed payments_test
+ store SetPremiumPayment test. Build/vet/gofmt/test green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
