docs: consolidate documentation into organized structure

- Move 12 markdown files from root to docs/ subdirectories
- Organize documentation by category:
  • docs/troubleshooting/ (1 file)  - Technical troubleshooting guides
  • docs/deployment/      (4 files) - Deployment and security documentation
  • docs/guides/          (3 files) - Feature-specific guides
  • docs/planning/        (4 files) - Planning and improvement proposals

Root directory cleanup:
- Reduced from 16 to 4 markdown files in root
- Only essential project files remain:
  • CLAUDE.md (AI instructions)
  • README.md (Main project readme)
  • CLEANUP_PLAN.md (Current cleanup plan)
  • SRC_STRUCTURE_IMPROVEMENTS.md (Structure improvements)

This improves:
✅ Documentation discoverability
✅ Logical organization by purpose
✅ Clean root directory
✅ Better maintainability

src/Framework/Vault/VaultInitializer.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Framework\Vault;
+
+use App\Framework\Attributes\Initializer;
+use App\Framework\Config\EnvKey;
+use App\Framework\Config\Environment;
+use App\Framework\Database\ConnectionInterface;
+use App\Framework\DI\Container;
+use App\Framework\Http\ServerEnvironment;
+use RuntimeException;
+
+/**
+ * Vault Initializer für DI Container
+ */
+final readonly class VaultInitializer
+{
+    public function __construct(
+        private Environment $environment,
+        private ConnectionInterface $connection,
+        private ServerEnvironment $serverEnvironment
+    ) {
+    }
+
+    #[Initializer]
+    public function __invoke(Container $container): Vault
+    {
+        // Encryption Key aus Environment
+        $encodedKey = $this->environment->get(EnvKey::VAULT_ENCRYPTION_KEY);
+
+        if ($encodedKey === null) {
+            throw new RuntimeException(
+                'VAULT_ENCRYPTION_KEY not set in environment. ' .
+                'Generate one with: php console.php vault:generate-key'
+            );
+        }
+
+        // Decode base64-encoded key
+        $encryptionKey = DatabaseVault::decodeKey($encodedKey);
+
+        // Audit Logger
+        $auditLogger = new VaultAuditLogger($this->connection);
+
+        // Client IP und User Agent für Audit Logging
+        $clientIp = $this->serverEnvironment->getClientIp();
+        $userAgent = $this->serverEnvironment->getUserAgent();
+
+        // DatabaseVault instance
+        return new DatabaseVault(
+            connection: $this->connection,
+            encryptionKey: $encryptionKey,
+            auditLogger: $auditLogger,
+            clientIp: $clientIp,
+            userAgent: $userAgent
+        );
+    }
+}