feat(payments): gate Solana and BTC production rails

[Svaag]

Summary

• Render the explicit EVM/Solana payment catalog, per-network receivers, CDP credentials, BTC receive-only xpub, native-asset allowlist, and worker heartbeat threshold from Vault.
• Require Solana capability and BTC worker readiness through the post-deploy payment-catalog gate.
• Add alerts for Solana verify/settle failures, native worker unavailability, and pending-intent scan lag.
• Document the reviewed production catalog and a paid mainnet EVM/Solana/BTC canary with kill switches and rollback steps.
• Extend deployment preflight contracts without changing application SHA pins.

Why

Enabling payment code is not sufficient evidence that a rail can safely accept funds. Promotion must fail closed when CDP does not advertise Solana support or the durable BTC scanner is unhealthy.

Impact

Cloud deployments now require the production payment secrets and wait for the payment catalog to prove Solana and BTC readiness. Operators gain explicit alerts, canary evidence, and rail-specific kill switches.

Zcash is intentionally excluded. The prior research PR AS215932/hyrule-cloud#31 is deferred and closed.

Validation

• scripts/ci/iac-static.sh — 130 tests passed
• yamllint -c .yamllint .
• Syntax checks passed for every Ansible playbook
• scripts/ci/deploy-preflight.sh through the static IaC suite
• git diff --check

promtool was unavailable locally; the rules passed repository YAML/static validation and should still run through the normal monitoring CI gate.

Rollout

Merge only after the cloud and web companion PRs are available. Populate reviewed Vault values, deploy through the normal approval path, and execute the paid canary before marking the rails production-ready.

Companion PRs

• Cloud API, facilitator integration, and BTC readiness: feat(payments): add Solana x402 and BTC rail readiness hyrule-cloud#77
• Web checkout: feat(payments): add Solana x402 checkout hyrule-web#39
• Deferred Zcash research: [deferred] research: x402 Zcash binding hyrule-cloud#31