feat(tournament): add mini championship functionality and enhance tournament class handling

- Introduced addMiniChampionship method in tournamentService to create tournaments with predefined classes for mini championships.
- Updated getTournaments method to filter tournaments based on type, including support for mini championships.
- Enhanced TournamentClass model to include maxBirthYear for age class restrictions.
- Modified tournamentController and tournamentRoutes to support new mini championship endpoint.
- Updated frontend components to manage mini championship creation and display, including localization for new terms.

backend/routes/tournamentRoutes.js

@@ -2,6 +2,7 @@ import express from 'express';
 import {
   getTournaments,
   addTournament,
+  addMiniChampionship,
   updateTournament,
   addParticipant,
   getParticipants,
@@ -105,6 +106,9 @@ router.get('/stages', authenticate, getStages);
 router.put('/stages', authenticate, upsertStages);
 router.post('/stages/advance', authenticate, advanceStage);
 
+// Minimeisterschaft anlegen (vor :clubId, damit 'mini' nicht als clubId matcht)
+router.post('/mini', authenticate, addMiniChampionship);
+
 // Muss NACH allen festen Pfaden stehen, sonst matcht z.B. '/stages' als clubId='stages'
 router.get('/:clubId', authenticate, getTournaments);
 router.post('/', authenticate, addTournament);