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

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+<?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,
+        ];
+    }
+}

database/factories/CreditWalletFactory.php

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+<?php
+
+namespace Database\Factories;
+
+use App\Models\CreditWallet;
+use App\Models\User;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/**
+ * @extends Factory<CreditWallet>
+ */
+class CreditWalletFactory extends Factory
+{
+    /**
+     * @return array<string, mixed>
+     */
+    public function definition(): array
+    {
+        return [
+            'user_id' => User::factory(),
+            'balance_credits' => 0,
+        ];
+    }
+
+    public function withBalance(int $credits): static
+    {
+        return $this->state(fn (): array => ['balance_credits' => $credits]);
+    }
+}

database/migrations/2026_06_17_141218_create_credit_wallets_table.php

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+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * Credit-Wallet laut Decision-Update (Rev. 4): eine Wallet pro User, ein
+ * tier-abhängiger Preis. 1 Credit = 1 €. Der Saldo ist die Summe aller
+ * Buchungen in `credit_transactions` und wird hier denormalisiert geführt,
+ * damit Gate-Checks ohne Aggregat-Query auskommen.
+ */
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('credit_wallets', function (Blueprint $table): void {
+            $table->id();
+            $table->foreignId('user_id')->unique()->constrained()->cascadeOnDelete();
+            $table->integer('balance_credits')->default(0);
+            $table->timestamps();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('credit_wallets');
+    }
+};

database/migrations/2026_06_17_141219_create_credit_transactions_table.php

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+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+/**
+ * Append-only Ledger der Credit-Wallet. Jede Auf-/Entladung ist eine Zeile
+ * mit vorzeichenbehaftetem `amount_credits` (+ = Gutschrift, − = Verbrauch)
+ * und dem resultierenden `balance_after` für lückenlose Nachvollziehbarkeit.
+ * `reference` verweist polymorph auf den auslösenden Vorgang (SinglePurchase,
+ * Boost, PressRelease …).
+ */
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('credit_transactions', function (Blueprint $table): void {
+            $table->id();
+            $table->foreignId('credit_wallet_id')->constrained()->cascadeOnDelete();
+            $table->foreignId('user_id')->constrained()->cascadeOnDelete();
+            $table->integer('amount_credits');
+            $table->integer('balance_after');
+            $table->string('type');
+            $table->string('description')->nullable();
+            $table->nullableMorphs('reference');
+            $table->timestamps();
+
+            $table->index(['user_id', 'created_at']);
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('credit_transactions');
+    }
+};