Refactor TimefixService to improve query handling and enhance error management in MainActivity. Update AndroidManifest to specify application class and increment Gradle version. Enhance BookingViewModel for better state management and loading indicators. Update UI components for improved user experience in booking screens.

backend/src/services/TimefixService.js

@@ -33,15 +33,15 @@ class TimefixService {
     });
     
     // Hole auch die Timefixes für diese Einträge
-    const entryIds = entries.map(e => e.id);
+    const entryIds = entries.map(e => e.id).filter(Boolean);
     if (entryIds.length === 0) {
       return [];
     }
 
     const timefixesForEntries = await sequelize.query(
-      `SELECT worklog_id, fix_type, fix_date_time FROM timefix WHERE worklog_id IN (?)`,
+      `SELECT worklog_id, fix_type, fix_date_time FROM timefix WHERE worklog_id IN (:entryIds)`,
       {
-        replacements: [entryIds],
+        replacements: { entryIds },
         type: sequelize.QueryTypes.SELECT
       }
     );