feat: add UserResource with is_admin toggle and delete

User management resource with editable is_admin field, postcode support,
admin filter, and inline delete action. Includes list and edit pages.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Filament/Resources/OilPredictionResource.php

@@ -4,6 +4,7 @@ namespace App\Filament\Resources;
 
 use App\Enums\PredictionSource;
 use App\Enums\TrendDirection;
+use App\Filament\NavigationGroup;
 use App\Filament\Resources\OilPredictionResource\Pages\ListOilPredictions;
 use App\Filament\Resources\OilPredictionResource\Pages\ViewOilPrediction;
 use App\Models\PricePrediction;
@@ -23,9 +24,7 @@ class OilPredictionResource extends Resource
 {
     protected static ?string $model = PricePrediction::class;
 
-    protected static string|\BackedEnum|null $navigationIcon = 'heroicon-o-beaker';
-
-    protected static string|\UnitEnum|null $navigationGroup = 'Data';
+    protected static string|\UnitEnum|null $navigationGroup = NavigationGroup::Data;
 
     protected static ?string $navigationLabel = 'Oil Predictions';