feat: add StatsOverviewWidget to admin dashboard

Four-stat overview widget (users, stations, oil prediction, API errors)
with 30s polling registered on the admin panel dashboard.

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

app/Filament/Widgets/StatsOverviewWidget.php

@@ -0,0 +1,84 @@
+<?php
+
+namespace App\Filament\Widgets;
+
+use App\Models\ApiLog;
+use App\Models\PricePrediction;
+use App\Models\Station;
+use App\Models\User;
+use Carbon\Carbon;
+use Filament\Widgets\StatsOverviewWidget as BaseWidget;
+use Filament\Widgets\StatsOverviewWidget\Stat;
+
+class StatsOverviewWidget extends BaseWidget
+{
+    protected ?string $pollingInterval = '30s';
+
+    protected function getStats(): array
+    {
+        return [
+            $this->usersStat(),
+            $this->stationsStat(),
+            $this->oilPredictionStat(),
+            $this->apiErrorsStat(),
+        ];
+    }
+
+    private function usersStat(): Stat
+    {
+        return Stat::make('Total users', User::count())
+            ->icon('heroicon-o-users')
+            ->color('primary');
+    }
+
+    private function stationsStat(): Stat
+    {
+        $count = Station::count();
+        $lastSeen = Station::max('last_seen_at');
+        $description = $lastSeen
+            ? 'Last seen '.Carbon::parse($lastSeen)->diffForHumans()
+            : 'No stations yet';
+
+        return Stat::make('Stations in DB', number_format($count))
+            ->description($description)
+            ->icon('heroicon-o-map-pin')
+            ->color('success');
+    }
+
+    private function oilPredictionStat(): Stat
+    {
+        $prediction = PricePrediction::latest('generated_at')->first();
+
+        if ($prediction === null) {
+            return Stat::make('Latest oil prediction', 'None')
+                ->icon('heroicon-o-beaker')
+                ->color('gray');
+        }
+
+        $ageHours = $prediction->generated_at->diffInHours(now());
+        $color = $ageHours > 24 ? 'warning' : 'success';
+        $value = ucfirst($prediction->direction->value)
+            .' · '.$prediction->confidence.'%'
+            .' · '.strtoupper($prediction->source->value);
+
+        return Stat::make('Latest oil prediction', $value)
+            ->description('Generated '.$prediction->generated_at->diffForHumans())
+            ->icon('heroicon-o-beaker')
+            ->color($color);
+    }
+
+    private function apiErrorsStat(): Stat
+    {
+        $errors = ApiLog::where('created_at', '>=', now()->subDay())
+            ->where(fn ($q) => $q->where('status_code', '>=', 400)
+                ->orWhereNull('status_code')
+                ->orWhereNotNull('error'))
+            ->count();
+
+        $color = $errors > 0 ? 'danger' : 'success';
+
+        return Stat::make('API errors (24h)', $errors)
+            ->icon('heroicon-o-exclamation-triangle')
+            ->color($color);
+    }
+}

app/Providers/Filament/AdminPanelProvider.php

@@ -2,6 +2,7 @@
 
 namespace App\Providers\Filament;
 
+use App\Filament\Widgets\StatsOverviewWidget;
 use Filament\Http\Middleware\Authenticate;
 use Filament\Http\Middleware\AuthenticateSession;
 use Filament\Http\Middleware\DisableBladeIconComponents;
@@ -39,6 +40,7 @@ class AdminPanelProvider extends PanelProvider
             ->discoverWidgets(in: app_path('Filament/Widgets'), for: 'App\Filament\Widgets')
             ->widgets([
                 AccountWidget::class,
+                StatsOverviewWidget::class,
             ])
             ->middleware([
                 EncryptCookies::class,

tests/Feature/Admin/StatsOverviewWidgetTest.php

@@ -0,0 +1,26 @@
+<?php
+
+use App\Filament\Widgets\StatsOverviewWidget;
+use App\Models\ApiLog;
+use App\Models\PricePrediction;
+use App\Models\Station;
+use App\Models\User;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Livewire\Livewire;
+
+uses(RefreshDatabase::class);
+
+beforeEach(function () {
+    $this->admin = User::factory()->admin()->create();
+    $this->actingAs($this->admin);
+});
+
+it('renders the stats overview widget', function () {
+    User::factory()->count(3)->create();
+    Station::factory()->count(2)->create();
+    PricePrediction::factory()->create(['generated_at' => now()->subHours(2)]);
+    ApiLog::factory()->count(2)->create(['status_code' => 200, 'error' => null, 'created_at' => now()->subMinutes(30)]);
+
+    Livewire::test(StatsOverviewWidget::class)
+        ->assertOk();
+});