Rename package to mattitja/laravel-plausible-proxy

- Rename Composer package to mattitja/laravel-plausible-proxy and
  namespace to Mattitja\LaravelPlausibleProxy
- Point homepage and links to git.mattitja.se
- Forward only User-Agent and visitor IP (X-Forwarded-For) to Plausible
  instead of all request headers
- Forward all event fields and return Plausible's upstream response
- Accept props as array or JSON string
- Drop Laravel 10, upgrade Larastan to 3 and PHPStan plugins to 2
- Remove broken facade alias and dead autoload paths
- Clean up README, issue template and remove invalid FUNDING.yml

.github/workflows/run-tests.yml

@@ -56,10 +56,6 @@ jobs:
           echo "::add-matcher::${{ runner.tool_cache }}/php.json"
           echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
 
-      - name: Remove Larastan if Laravel 12
-        if: startsWith(matrix.laravel, '12.')
-        run: composer remove larastan/larastan --dev --no-update || true
-
       - name: Install dependencies
         run: |
           composer require \