Migrate from Yarn to npm, add unit tests, update dependencies

[luispabon]

Summary

Migrate the frontend build tooling from Yarn to npm, replace the Bower-based font-awesome dependency with the direct npm package, add unit tests for several domain classes, and clean up Dockerfile/Makefile.

Changes

Build tooling migration (Yarn → npm)

• Dockerfile: Replace yarn install with npm ci, yarn build:css with npm run build:css, copy package-lock.json instead of yarn.lock, add WORKDIR /application for correct paths
• Makefile: Replace yarn-install target with npm-install, update build-css to use npm, update install-dependencies dependency chain
• package.json: Remove @bower_components/font-awesome dependency, add font-awesome (npm), switch engines from yarn to npm

Dockerfile cleanup

• Fix as → AS (uppercase for consistency)
• Improve comment wording for clarity
• Fix asset copy paths to use correct /application/ prefix and copy font-awesome directly instead of the entire @bower_components directory

Dependency updates

• Pinned dev dependency versions: autoprefixer ^10.5.0, postcss ^8.5.15, postcss-cli ^11.0.1, tailwindcss ^3.4.19
• Replaced yarn.lock with package-lock.json (npm lockfile v3)

New tests

• tests/Unit/PHPDocker/Project/ProjectTest.php — Unit tests for the Project model
• tests/Unit/PHPDocker/Project/ServiceOptions/MemcachedTest.php — Unit tests for Memcached service options
• tests/Unit/Assert/PostgresTypeValidatorTest.php — Unit tests for PostgresTypeValidator
• tests/Functional/GeneratorTest.php — Expanded functional test coverage