Ability to constrain selectable blueprints based on requirements

## Describe your feature request

I have a Blueprint annotated with the `@requires` jsdoc. It would be amazing to generate a DAG based on these and only render selectable blueprints in the UI.

## Describe the solution you'd like

- A user annotates their blueprint with `@requires` and specifies 'my-blueprint' as the value.
- In the UI, if a user is creating a new project - all @requires blueprints should not be selectable as they require a blueprint to already be deployed.
- in the UI, if a user is adding a blueprint to an existing project, only blueprints which satisfy the `@requires` should be selectable.

## Describe alternatives you've considered

- Throw an error at synth time (this is not a great UX).

## Additional context

N/A

Start by tracing how the @requires JSDoc annotation is represented and how the UI builds its selectable blueprint lists. Define the dependency DAG and verify both flows: required blueprints are excluded for new projects, while existing projects show only blueprints whose requirements are satisfied.

Written by the indexing model from the issue text.