Multi-blueprint selection during project creation

## Describe your feature request

When navigating to the CodeCatalyst 'CreateProject' page, it would be amazing to be able to select multiple blueprints at once and have the wizard dynamically load the config pages for each selection (in dependency order) which would save the user having to create them serially.

## Describe the solution you'd like

A way to select multiple blueprints at project creation time (and also if trying to add to an existing project too) and have them all processed atomically.

## Describe alternatives you've considered

N/A

## Additional context

N/A

Start with the CodeCatalyst “CreateProject” page and its blueprint-selection flow. Define how multiple selections, dependency-ordered configuration pages, and atomic processing should work both during project creation and when adding blueprints to an existing project; done means both workflows support the full selection without serial creation.

Written by the indexing model from the issue text.