Warenwirtschaft: OPT-1 Quick Wins + Entwicklungsplan V6.0

- N+1-Fix Ausschussliste: user.account eager laden (StockDisposalController@index)
- Composite-Indizes stock_entries(entry_type,status,ingredient_id/packaging_item_id) für InventoryService-Aggregationen
- Ungenutzten Eager-Load producedByUser aus ProductionRepository::listForIndex entfernt
- ExampleTest auf assertRedirect umgestellt (Suite 100% grün: 155 Tests)
- Query-Count-Regressionstest für die Ausschussliste
- Plan V6.0 (Code-Verifikation, OPT-Block, geklärte Kundenfragen)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

database/migrations/2026_07_06_113731_add_aggregation_indexes_to_stock_entries_table.php

@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Bestands-Aggregationen (InventoryService) filtern durchgängig auf
+     * (entry_type, status) und gruppieren nach ingredient_id bzw. packaging_item_id.
+     */
+    public function up(): void
+    {
+        Schema::table('stock_entries', function (Blueprint $table) {
+            $table->index(['entry_type', 'status', 'ingredient_id'], 'stock_entries_type_status_ingredient_index');
+            $table->index(['entry_type', 'status', 'packaging_item_id'], 'stock_entries_type_status_packaging_index');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('stock_entries', function (Blueprint $table) {
+            $table->dropIndex('stock_entries_type_status_ingredient_index');
+            $table->dropIndex('stock_entries_type_status_packaging_index');
+        });
+    }
+};