feat(cli): add interactive extension multiselect

[ulises-jeremias]

Summary

• Adds CNA-style interactive extension selection after template choice
• Filters extensions by the selected template type plus catalog-wide all
• Prompts extension categories first, then extensions within selected categories
• Passes selected extension URLs into addons for scaffold

Closes#163

CNA reference

• packages/create-awesome-node-app/src/options.ts extension flow
• packages/create-awesome-node-app/src/templates.tsgetAllExtensionsWithCategory

Test plan

• uv run ruff check packages/create-awesome-python-app/src/create_awesome_python_app/catalog.py packages/create-awesome-python-app/src/create_awesome_python_app/cli.py packages/create-awesome-python-app/tests/test_catalog_resolve.py packages/create-awesome-python-app/tests/test_interactive.py
• uv run pytest packages/create-awesome-python-app/tests/test_catalog_resolve.py packages/create-awesome-python-app/tests/test_interactive.py -q
• uv run pyright packages/create-awesome-python-app/src/create_awesome_python_app/cli.py packages/create-awesome-python-app/src/create_awesome_python_app/catalog.py

Review notes

This PR is stacked on #174, which is stacked on #173. It intentionally does not implement customOptions (#164).

Made with Cursor