Add lifecycle-managed Stripe environment syncing

[davejohnson]

What changed

• add declarative payments.stripe environment configuration for development, staging, and production
• resolve scoped Stripe connections and synchronize publishable/secret keys plus selected price IDs into hosting environments through spec → plan → apply
• add stale-plan fingerprints, collision validation, CI deploy deferral, and safety checks that prevent live Stripe credentials from being treated as sandbox data
• document migration from the Invoice Express Stripe/Railway sync scripts
• add schema, planning, convergence, service, and payments-tool coverage

Why

Invoice Express currently relies on imperative scripts to copy Stripe configuration and price IDs into hosting environments. This brings that workflow into Hypervibe's desired-state lifecycle so drift is planned, applied, audited, and verified consistently across development, staging, and production.

Impact

Projects can declare how Stripe environments map to hosting environments and let Hypervibe safely converge the corresponding environment variables. Existing legacy Stripe connection fields remain supported.

Validation

• npm test — 106 files, 835 tests passed
• npm run typecheck
• npm run build
• git diff --check