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

routes/api.php

@@ -1,6 +1,6 @@
 <?php
 
 use Illuminate\Support\Facades\Route;
-use MattitjaAB\LaravelPlausibleProxy\Http\Controllers\PlausibleEventApiController;
+use Mattitja\LaravelPlausibleProxy\Http\Controllers\PlausibleEventApiController;
 
 Route::post('api/event', PlausibleEventApiController::class);