feat(tournament): adjust mini championship year label and winning sets logic

- Updated the German localization for the mini championship year label to simplify the text.
- Introduced a new reactive property to dynamically set the number of winning sets based on the mini championship type, defaulting to 1 for mini championships.

frontend/src/i18n/locales/de.json

@@ -563,7 +563,7 @@
     "openTournaments": "Offene Turniere",
     "miniChampionships": "Minimeisterschaften",
     "newMiniChampionship": "Neue Minimeisterschaft",
-    "miniChampionshipYear": "Jahr (Altersstufen)",
+    "miniChampionshipYear": "Jahr",
     "miniChampionshipYearHint": "12 = in diesem Jahr 11 oder 12 Jahre, 10 = 9 oder 10, 8 = 8 oder jünger",
     "miniChampionshipLocation": "Ort",
     "tournamentParticipations": "Turnierteilnahmen",

frontend/src/views/TournamentTab.vue

@@ -953,6 +953,12 @@ export default {
                 }
             },
             immediate: false
+        },
+        isMiniChampionship: {
+            handler(val) {
+                this.newWinningSets = val ? 1 : 3;
+            },
+            immediate: true
         }
     },
     async created() {
@@ -1639,7 +1645,7 @@ export default {
                 this.newDate = '';
                 this.newMiniOrt = '';
                 this.newMiniYear = new Date().getFullYear();
-                this.newWinningSets = 3;
+                this.newWinningSets = 1;
             } catch (error) {
                 console.error('Fehler beim Anlegen der Minimeisterschaft:', error);
                 const message = safeErrorMessage(error, this.$t('tournaments.errorCreatingTournament'));