Add termination (Kündigung) functionality and related translations

- Implemented the ability to initiate terminations from Mietverhältnisse.
- Added new fields and options for terminations in both German and English language files.
- Updated metadata definitions to include relationships for terminations with Mietobjekte and Beteiligte.
- Enhanced the service layer to handle termination creation, including linking relevant entities and copying documents.
- Updated configuration timestamps for deployment.

custom/Espo/Custom/Controllers/CVmhMietverhltnis.php

@@ -42,4 +42,22 @@ class CVmhMietverhltnis extends \Espo\Core\Templates\Controllers\BasePlus
         
         return $result;
     }
+    
+    /**
+     * POST Action: Initiate termination (Kündigung) from Mietverhältnis
+     */
+    public function postActionInitiateTermination(Request $request): array
+    {
+        $data = $request->getParsedBody();
+        
+        $id = $data->id ?? null;
+        if (!$id) {
+            throw new BadRequest('No Mietverhältnis ID provided');
+        }
+        
+        $service = $this->getRecordService();
+        $result = $service->initiateTermination($id);
+        
+        return $result;
+    }
 }