Add NPC creation status tracking and progress reporting in Admin module

- Implemented getNPCsCreationStatus method in AdminController to retrieve the status of NPC creation jobs.
- Enhanced AdminService to manage NPC creation jobs, including job ID generation, progress updates, and error handling.
- Updated frontend CreateNPCView to display progress of NPC creation, including estimated time remaining and job status.
- Added localization strings for progress reporting in both German and English.
- Improved overall user experience by providing real-time feedback during NPC creation processes.

frontend/src/i18n/locales/en/admin.json

@@ -162,7 +162,13 @@
                 "errorCreating": "Error creating NPCs.",
                 "invalidAgeRange": "Invalid age range.",
                 "invalidTitleRange": "Invalid title range.",
-                "invalidCount": "Invalid count (1-500)."
+                "invalidCount": "Invalid count (1-500).",
+                "progress": "Progress",
+                "progressDetails": "{current} of {total} NPCs created",
+                "timeRemainingSeconds": "Time remaining: {seconds} seconds",
+                "timeRemainingMinutes": "Time remaining: {minutes} minutes {seconds} seconds",
+                "almostDone": "Almost done...",
+                "jobNotFound": "Job not found or expired."
             }
         },
         "chatrooms": {