Fix R15: no weak admin fallback in prod; validate device room update

- DatabaseSeeder throws outside local/testing when HOMEOS_ADMIN_PASSWORD is
  unset, instead of silently seeding the documented `homeos-dev` password
  (bootstrap always runs migrate --seed, so a prod misconfig must fail loudly).
- Devices\Show::saveRoom validates roomId as nullable|exists:rooms,id, so a
  crafted request can no longer trigger a foreign-key 500. Added a feature test.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/Livewire/Devices/Show.php

@@ -37,6 +37,7 @@ class Show extends Component
 
     public function saveRoom(): void
     {
+        $this->validate(['roomId' => ['nullable', 'integer', 'exists:rooms,id']]);
         $this->device->update(['room_id' => $this->roomId ?: null]);
         $this->flashMessage(__('devices.saved'));
     }

database/seeders/DatabaseSeeder.php

@@ -15,9 +15,17 @@ class DatabaseSeeder extends Seeder
      */
     public function run(): void
     {
-        // `?:` (not env's 2nd arg) so a present-but-empty HOMEOS_ADMIN_PASSWORD can never
-        // seed a blank-password admin — it falls back to a non-empty dev default.
-        $adminPassword = env('HOMEOS_ADMIN_PASSWORD') ?: 'homeos-dev';
+        // The admin password must be explicit outside local/testing — never silently seed a
+        // known credential in production. The dev fallback only applies to local/testing.
+        $adminPassword = env('HOMEOS_ADMIN_PASSWORD');
+
+        if (blank($adminPassword)) {
+            if (! app()->environment('local', 'testing')) {
+                throw new \RuntimeException('HOMEOS_ADMIN_PASSWORD must be set to seed the admin account outside local/testing.');
+            }
+
+            $adminPassword = 'homeos-dev';
+        }
 
         User::updateOrCreate(
             ['email' => env('HOMEOS_ADMIN_EMAIL', 'admin@homeos.local')],

tests/Feature/HomeTest.php

@@ -2,12 +2,14 @@
 
 namespace Tests\Feature;
 
+use App\Livewire\Devices\Show;
 use App\Models\Device;
 use App\Models\DeviceState;
 use App\Models\Entity;
 use App\Models\Room;
 use App\Models\User;
 use Illuminate\Foundation\Testing\RefreshDatabase;
+use Livewire\Livewire;
 use Tests\TestCase;
 
 class HomeTest extends TestCase
@@ -55,4 +57,18 @@ class HomeTest extends TestCase
             ->assertSee(__('dashboard.warnings_title'))
             ->assertSee('Türsensor');
     }
+
+    public function test_device_room_update_rejects_invalid_room(): void
+    {
+        $device = Device::create(['name' => 'Lampe', 'status' => 'active', 'last_seen_at' => now()]);
+
+        $this->actingAs(User::factory()->create());
+
+        Livewire::test(Show::class, ['device' => $device])
+            ->set('roomId', 999999)
+            ->call('saveRoom')
+            ->assertHasErrors('roomId');
+
+        $this->assertNull($device->fresh()->room_id);
+    }
 }