feat(TournamentStats): add internal tournament statistics endpoint and localization updates

- Implemented a new endpoint `getInternalTournamentStats` in the tournament controller to retrieve statistics for internal tournaments based on club ID and selected months.
- Enhanced the tournament service to compute player statistics, including absolute and average rankings.
- Updated tournament routes to include the new statistics endpoint.
- Added localization strings for internal tournament statistics in multiple languages, improving user accessibility and experience.
- Integrated the new statistics component into the TournamentsView for better user interaction.

backend/controllers/tournamentController.js

@@ -59,6 +59,20 @@ export const getTournaments = async (req, res) => {
     }
 };
 
+/** Ranglisten interne Einzel-Turniere (Gruppen- + K.-o.-Punkte) */
+export const getInternalTournamentStats = async (req, res) => {
+    const { authcode: token } = req.headers;
+    const { clubId } = req.params;
+    const months = req.query.months;
+    try {
+        const data = await tournamentService.getInternalTournamentPlayerStats(token, clubId, months);
+        res.status(200).json(data);
+    } catch (error) {
+        console.error(error);
+        res.status(500).json({ error: error.message });
+    }
+};
+
 // 2. Neues Turnier anlegen
 export const addTournament = async (req, res) => {
     const { authcode: token } = req.headers;