Credit-Wallet + Ledger + Tier-Preisableitung (Fundament)

Echte Credit-Wallet (1 Credit = 1 EUR) mit append-only Ledger als Basis fuer
die Credit-Oekonomie aus dem Decision-Update (Rev. 4):

- credit_wallets (denormalisierter Saldo) + credit_transactions (Ledger,
  vorzeichenbehaftet, balance_after, polymorphe reference)
- CreditWalletService: einziger Schreibpfad, atomar mit Row-Lock,
  InsufficientCreditsException mit shortfall fuer den Mini-Checkout
- Tier-Enum (Einzel/Starter/Business/Pro/Agency) + User::currentTier()
- CreditPricingService: tier-gestaffelte Ableitung aus config/credits.php
  (Extra-PM 19/15/12/10/8, Boost 12/20/35, PDF 3, Depublish 25, Pruef-Quota)

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

database/factories/CreditTransactionFactory.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Database\Factories;
+
+use App\Enums\CreditTransactionType;
+use App\Models\CreditTransaction;
+use App\Models\CreditWallet;
+use App\Models\User;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/**
+ * @extends Factory<CreditTransaction>
+ */
+class CreditTransactionFactory extends Factory
+{
+    /**
+     * @return array<string, mixed>
+     */
+    public function definition(): array
+    {
+        $amount = $this->faker->numberBetween(1, 50);
+
+        return [
+            'credit_wallet_id' => CreditWallet::factory(),
+            'user_id' => User::factory(),
+            'amount_credits' => $amount,
+            'balance_after' => $amount,
+            'type' => CreditTransactionType::Topup,
+            'description' => null,
+            'reference_type' => null,
+            'reference_id' => null,
+        ];
+    }
+}