refactor : rename GITEA_ENCRYPTION_KEY to ENCRYPTION_KEY

Generic encryption key name for shared use across Gitea and BookStack
token encryption.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Service/TokenEncryptor.php

@@ -4,7 +4,6 @@ declare(strict_types=1);
 
 namespace App\Service;
 
-use App\Exception\GiteaApiException;
 use RuntimeException;
 use SodiumException;
 use Symfony\Component\DependencyInjection\Attribute\Autowire;
@@ -15,7 +14,7 @@ final class TokenEncryptor
     private readonly bool $configured;
 
     public function __construct(
-        #[Autowire('%env(GITEA_ENCRYPTION_KEY)%')]
+        #[Autowire('%env(ENCRYPTION_KEY)%')]
         string $encryptionKey,
     ) {
         if ('' === $encryptionKey) {
@@ -75,7 +74,7 @@ final class TokenEncryptor
     private function assertConfigured(): void
     {
         if (!$this->configured) {
-            throw new GiteaApiException('Gitea encryption is not configured. Please set a valid GITEA_ENCRYPTION_KEY.');
+            throw new RuntimeException('Encryption is not configured. Please set a valid ENCRYPTION_KEY.');
         }
     }
 }