fix: ensure Filter receives current HTTP request when resolved from DI container

Fixes #30 - Request parameters not included in filter object pulled from DI container

When using dependency injection in controllers like:
  public function index(PostFilter $postFilter)

The filter methods were not being called because Laravel's DI container
was creating a new empty Request instance instead of using the current
HTTP request.

Changes:
- Add bindIf() in FilterableServiceProvider to ensure Request::class
  resolves to the current HTTP request ($app['request'])
- Add comprehensive test suite for DI container resolution scenarios

The fix ensures that DI-resolved filters behave identically to manually
instantiated filters using new PostFilter(request()).

Author: Thavarshan

src/Filterable/Providers/FilterableServiceProvider.php

@@ -3,6 +3,7 @@
 namespace Filterable\Providers;
 
 use Filterable\Console\MakeFilterCommand;
+use Illuminate\Http\Request;
 use Spatie\LaravelPackageTools\Package;
 use Spatie\LaravelPackageTools\PackageServiceProvider;
 
@@ -18,6 +19,30 @@ public function configurePackage(Package $package): void
             ->hasCommand(MakeFilterCommand::class);
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function packageRegistered(): void
+    {
+        $this->registerFilterBindings();
+    }
+
+    /**
+     * Register contextual bindings for Filter classes.
+     *
+     * This ensures that when a Filter subclass is resolved from the DI container,
+     * it receives the current HTTP request instance rather than an empty Request.
+     */
+    protected function registerFilterBindings(): void
+    {
+        // Bind Request class to resolve to the current request from the container.
+        // This ensures Filter subclasses get the active HTTP request instead of an empty one.
+        // The rebinding allows the test suite to override with $app->instance() if needed.
+        $this->app->bindIf(Request::class, function ($app) {
+            return $app['request'];
+        });
+    }
+
     /**
      * {@inheritdoc}
      */