feat: add --json output for --list-templates and --list-addons

[ulises-jeremias]

Problem

--list-templates and --list-addons only print human-readable text. Scripts, CI, and the website sync need machine-readable JSON (parity with Create-Node-App #230).

Solution

1. Add a --json flag on the CLI.
2. When combined with --list-templates / --list-addons, emit valid JSON (array/object) parseable by jq.
3. Keep the default human-readable format unchanged.
4. Add a small unit/integration test.

Acceptance criteria

• create-awesome-python-app --list-templates --json | jq . succeeds
• create-awesome-python-app --template fastapi-starter --list-addons --json | jq . succeeds
• Non-JSON listing behavior unchanged
• Test covers both list modes

Files

• packages/create-awesome-python-app/ CLI entry + list helpers
• matching tests under packages/