feat(tournament): implement class merging and pool management features

- Added mergeClassesIntoPool and resetPool functions in tournamentService to handle merging classes into a common pool and resetting pool assignments.
- Introduced new API routes for merging and resetting pools in tournamentRoutes.
- Enhanced TournamentGroupsTab component with UI for merging classes, including selection for source and target classes, strategy options, and out-of-competition settings.
- Updated localization files to include new strings related to class merging functionality.
- Modified TournamentTab to handle merge pool events and manage API interactions for merging classes.

backend/controllers/tournamentController.js

@@ -4,6 +4,42 @@ import { emitTournamentChanged } from '../services/socketService.js';
 import TournamentClass from '../models/TournamentClass.js';
 import HttpError from '../exceptions/HttpError.js';
 
+// Pools (zusammengelegte Gruppenphasen)
+export const mergeClassesIntoPool = async (req, res) => {
+    const { authcode: token } = req.headers;
+    const { clubId, tournamentId, sourceClassId, targetClassId, strategy, outOfCompetitionForSource } = req.body;
+    try {
+        await tournamentService.mergeClassesIntoPool(
+            token,
+            clubId,
+            tournamentId,
+            sourceClassId,
+            targetClassId,
+            strategy, // 'singleGroup' | 'distribute'
+            !!outOfCompetitionForSource
+        );
+        // Broadcast
+        emitTournamentChanged(clubId, tournamentId);
+        res.status(200).json({ success: true });
+    } catch (error) {
+        console.error('[mergeClassesIntoPool] Error:', error);
+        res.status(500).json({ error: error.message });
+    }
+};
+
+export const resetPool = async (req, res) => {
+    const { authcode: token } = req.headers;
+    const { clubId, tournamentId, poolId } = req.body;
+    try {
+        await tournamentService.resetPool(token, clubId, tournamentId, poolId);
+        emitTournamentChanged(clubId, tournamentId);
+        res.status(200).json({ success: true });
+    } catch (error) {
+        console.error('[resetPool] Error:', error);
+        res.status(500).json({ error: error.message });
+    }
+};
+
 // 1. Alle Turniere eines Vereins
 export const getTournaments = async (req, res) => {
     const { authcode: token } = req.headers;