Introduce spice_stock_movements ledger for traceable stock changes

Every delivery and batch now writes a signed movement entry instead of
directly incrementing/decrementing spice.quantity. The balance is always
the sum of all movements. Existing data is backfilled in the migration.
Rohstoff edit page shows the full movement history (Lagerbewegungen tab).

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

app/Filament/User/Resources/SpiceResource.php

@@ -78,7 +78,7 @@ class SpiceResource extends Resource
     public static function getRelations(): array
     {
         return [
-            //
+            RelationManagers\StockMovementsRelationManager::class,
         ];
     }
 

app/Filament/User/Resources/SpiceResource/RelationManagers/StockMovementsRelationManager.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace App\Filament\User\Resources\SpiceResource\RelationManagers;
+
+use Filament\Resources\RelationManagers\RelationManager;
+use Filament\Tables;
+use Filament\Tables\Table;
+
+class StockMovementsRelationManager extends RelationManager
+{
+    protected static string $relationship = 'stockMovements';
+    protected static ?string $title = 'Lagerbewegungen';
+
+    public function table(Table $table): Table
+    {
+        return $table
+            ->columns([
+                Tables\Columns\TextColumn::make('created_at')
+                    ->label('Datum')
+                    ->dateTime('d.m.Y H:i')
+                    ->sortable(),
+
+                Tables\Columns\TextColumn::make('description')
+                    ->label('Beschreibung'),
+
+                Tables\Columns\TextColumn::make('amount')
+                    ->label('Menge')
+                    ->formatStateUsing(fn ($state) => ($state > 0 ? '+' : '') . number_format($state, 2, ',', '.') . 'g')
+                    ->color(fn ($state) => $state > 0 ? 'success' : 'danger'),
+            ])
+            ->defaultSort('created_at', 'desc')
+            ->paginated([25, 50]);
+    }
+}

app/Filament/User/Resources/SpiceSupplierResource/Pages/CreateSpiceSupplier.php

@@ -4,17 +4,8 @@ namespace App\Filament\User\Resources\SpiceSupplierResource\Pages;
 
 use App\Filament\User\Resources\SpiceSupplierResource;
 use Filament\Resources\Pages\CreateRecord;
-use Illuminate\Database\Eloquent\Model;
-use App\Models\Spice;
 
 class CreateSpiceSupplier extends CreateRecord
 {
     protected static string $resource = SpiceSupplierResource::class;
-
-    protected function handleRecordCreation(array $data): Model {
-        $record = static::getModel()::create($data);
-
-        Spice::findOrFail($data['spice_id'])->increment('quantity', $data['amount']);
-        return $record;
-    }
 }

app/Filament/User/Resources/SpiceSupplierResource/Pages/EditSpiceSupplier.php

@@ -16,14 +16,9 @@ class EditSpiceSupplier extends EditRecord
                 ->requiresConfirmation()
                 ->modalHeading('Lieferung löschen')
                 ->modalDescription(fn ($record) => $record->spice && $record->spice->quantity < $record->amount
-                    ? 'Warnung: Nicht mehr genügend ' . $record->spice->name . ' im Lager. Der Bestand wird auf 0 gesetzt. Trotzdem löschen?'
+                    ? 'Warnung: Nach dem Löschen wird der Bestand von ' . $record->spice->name . ' negativ.'
                     : 'Soll diese Lieferung wirklich gelöscht werden?'
-                )
-                ->before(function ($record) {
-                    if ($record->spice) {
-                        $record->spice->decrement('quantity', $record->amount);
-                    }
-                }),
+                ),
         ];
     }
 }