fix(composer): simplify dependencies for hello world setup

[Snider]

Problem

composer.json requires packages that:

1. Aren't needed for a basic hello world Laravel app
2. Don't have repository URLs configured

"require": {
    "host-uk/core": "dev-main",
    "host-uk/core-admin": "dev-main",  // Not needed for basic setup
    "host-uk/core-api": "dev-main",    // Not needed for basic setup
    "host-uk/core-mcp": "dev-main"     // Not needed for basic setup
}

But only one repository is configured:

"repositories": [
    {"type": "vcs", "url": "https://github.com/host-uk/core-php.git"}
]

Running composer install fails:

Root composer.json requires host-uk/core-admin, it could not be found in any version

Solution

Either:

1. Simplify - Remove optional dependencies, keep only host-uk/core for a minimal template
2. Fix repos - Add missing VCS repository entries for all required packages

Option 1 is cleaner - a template should start minimal and users add what they need.

Expected Outcome

git clone https://github.com/host-uk/core-template my-app
cd my-app
composer install
cp .env.example .env
php artisan key:generate
php artisan serve
# Visit http://localhost:8000 -> Hello World