feat(library): add Stripe payment automation and alert guide

## Summary
- Add a Stripe payment-automation guide and cover image covering failed-payment alerts, current-state retrieval, deterministic routing, AI enrichment, and human approval.
- Keep the weighted comparison and verified totals, while replacing superlatives with specific capabilities and use-case guidance.

## Type of Change
- [x] Feature

## Testing
- bun run lint
- bun run type-check
- bun run check:audits
- bun run test
- Block-registry audit, focused library-content audit, and independent verification of comparison totals

## Checklist
- [x] Code follows project style guidelines
- [x] Self-reviewed my changes
- [ ] Tests added/updated and passing
- [x] No new warnings introduced
- [x] I confirm that I have read and agree to the terms outlined in the [Contributor License Agreement (CLA)](./CONTRIBUTING.md#contributor-license-agreement-cla)

Author: icecrasher321