Align installation guides with single-package delivery

[ancongui]

Several public guides still sent new applications to composer create-project firefly/skeleton on Packagist, although the skeleton now ships inside fireflyframework/larafly. Use the bundled firefly new installer throughout the quickstarts, tutorials, template README, and both book translations.

Describe optional adapters and component requirements as code already included in the root library, selected through configuration or satisfied through replace. Preserve the installer documentation's explicit bundled path-repository example.

Validation: 10 existing documentation tests pass (104 assertions), mkdocs build --strict passes, and git diff --check passes. Independently reviewed. Documentation only; the published v26.09.9 tag is unchanged.