feat(TrainingStats): enhance training statistics view and participant details

- Updated TrainingStatsService to include member details (first name, last name) in participant data.
- Modified TrainingDetailsDialog to remove unnecessary time display for training sessions.
- Added new filters for training days in TrainingStatsView, allowing users to select specific training days and view attending members.
- Enhanced localization files to support new training day filter and participant-related strings across multiple languages.

backend/services/trainingStatsService.js

@@ -205,7 +205,12 @@ class TrainingStatsService {
       include: [{
         model: Participant,
         as: 'participantList',
-        attributes: ['id', 'attendanceStatus']
+        attributes: ['id', 'memberId', 'attendanceStatus'],
+        include: [{
+          model: Member,
+          as: 'member',
+          attributes: ['id', 'firstName', 'lastName']
+        }]
       }],
       order: [['date', 'DESC']]
     });
@@ -215,7 +220,22 @@ class TrainingStatsService {
       date: day.date,
       participantCount: day.participantList
         ? day.participantList.filter((participant) => !participant.attendanceStatus || participant.attendanceStatus === 'present').length
-        : 0
+        : 0,
+      participants: day.participantList
+        ? day.participantList
+            .filter((participant) => !participant.attendanceStatus || participant.attendanceStatus === 'present')
+            .map((participant) => ({
+              id: participant.member?.id || participant.memberId,
+              firstName: participant.member?.firstName || '',
+              lastName: participant.member?.lastName || '',
+            }))
+            .filter((participant) => Number.isFinite(Number(participant.id)))
+            .sort((a, b) => {
+              const lastCompare = String(a.lastName || '').localeCompare(String(b.lastName || ''), 'de', { sensitivity: 'base' });
+              if (lastCompare !== 0) return lastCompare;
+              return String(a.firstName || '').localeCompare(String(b.firstName || ''), 'de', { sensitivity: 'base' });
+            })
+        : []
     }));
 
     const totalParticipants12Months = formattedTrainingDays.reduce((sum, day) => sum + (day.participantCount || 0), 0);