Add participant assignment to groups functionality

Implement a new endpoint to assign participants to specific groups within tournaments. This includes the addition of the `assignParticipantToGroup` function in the tournament controller, which handles the assignment logic and emits relevant events. Update the tournament routes to include this new functionality. Enhance the tournament service to manage group assignments and ensure proper statistics are calculated for participants. Additionally, update the frontend to support adding participants, including external ones, and reflect changes in the UI for group assignments.

backend/controllers/tournamentController.js

@@ -253,6 +253,28 @@ export const manualAssignGroups = async (req, res) => {
     }
 };
 
+export const assignParticipantToGroup = async (req, res) => {
+    const { authcode: token } = req.headers;
+    const { clubId, tournamentId, participantId, groupNumber, isExternal } = req.body;
+    
+    try {
+        const groups = await tournamentService.assignParticipantToGroup(
+            token,
+            clubId,
+            tournamentId,
+            participantId,
+            groupNumber,
+            isExternal || false
+        );
+        // Emit Socket-Event
+        emitTournamentChanged(clubId, tournamentId);
+        res.status(200).json(groups);
+    } catch (error) {
+        console.error('Error in assignParticipantToGroup:', error);
+        res.status(500).json({ error: error.message });
+    }
+};
+
 export const resetGroups = async (req, res) => {
     const { authcode: token } = req.headers;
     const { clubId, tournamentId } = req.body;