Refactor booking retrieval to return errors instead of nil values,
enabling more robust error handling throughout the booking, payment,
and PDF endpoints. Add custom HTTP error page rendering for not found
and internal server errors. Update interfaces and tests to match new
method signatures. This improves user feedback and code maintainability.
Introduce backend and frontend support for generating Stripe payment
links
for outstanding booking balances. Adds a new POST endpoint to create
payment
links, updates booking view to include a Stripe button, and integrates
error handling and feedback for payment link creation. Refactors view
models and templates to support the new feature.
