feat(TournamentConfigTab, TournamentResultsTab): enhance stage configuration and knockout actions

- Added ensureStageConfigurationPersisted method to validate and save stage advancements, ensuring proper configuration before advancing stages.
- Updated advanceStage method to call ensureStageConfigurationPersisted, improving the flow of tournament advancement.
- Introduced primary action buttons in TournamentResultsTab for starting and resetting knockout rounds, enhancing user interaction during tournament management.
- Styled results-primary-actions for better visibility and usability in the results tab.

frontend/src/components/tournament/TournamentConfigTab.vue

@@ -1962,6 +1962,33 @@ export default {
                 this.stageConfig.error = e?.message || String(e);
             }
         },
+        async ensureStageConfigurationPersisted(existingAdvancements = null) {
+            const advancements = Array.isArray(existingAdvancements) ? existingAdvancements : null;
+            if (advancements && advancements.length > 0) return;
+
+            const { stages, advancements: builtAdvancements } = this.buildPayload();
+            if (!Array.isArray(builtAdvancements) || builtAdvancements.length === 0) {
+                throw new Error(this.$t('tournaments.stageConfigLoadError'));
+            }
+
+            for (const adv of builtAdvancements) {
+                const hasPools = Array.isArray(adv?.config?.pools) && adv.config.pools.length > 0;
+                if (!hasPools) {
+                    const label = `${adv.fromStageIndex}→${adv.toStageIndex}`;
+                    throw new Error(this.$t('tournaments.atLeastOnePoolRule', { label }));
+                }
+            }
+
+            const saveRes = await apiClient.put('/tournament/stages', {
+                clubId: Number(this.clubId),
+                tournamentId: Number(this.tournamentId),
+                stages,
+                advancements: builtAdvancements,
+            });
+            if (saveRes.status >= 400) {
+                throw new Error(saveRes.data?.error || this.$t('messages.saveFailed'));
+            }
+        },
         async advanceStage(fromStageIndex, toStageIndex) {
             this.stageConfig.error = null;
             this.stageConfig.success = null;
@@ -1973,14 +2000,28 @@ export default {
                         tournamentId: Number(this.tournamentId)
                     }
                 });
-                const stages = Array.isArray(getRes?.data?.stages) ? getRes.data.stages : [];
-                const normalized = stages.map(s => ({
+                const advancements = Array.isArray(getRes?.data?.advancements) ? getRes.data.advancements : [];
+
+                // Alte Turniere haben teilweise Stages, aber noch keine gespeicherten Advancements.
+                // Dann ziehen wir die Konfiguration vor dem eigentlichen Start automatisch nach.
+                await this.ensureStageConfigurationPersisted(advancements);
+
+                const refreshedRes = advancements.length > 0
+                    ? getRes
+                    : await apiClient.get('/tournament/stages', {
+                        params: {
+                            clubId: Number(this.clubId),
+                            tournamentId: Number(this.tournamentId)
+                        }
+                    });
+                const refreshedStages = Array.isArray(refreshedRes?.data?.stages) ? refreshedRes.data.stages : [];
+                const refreshedNormalized = refreshedStages.map(s => ({
                     stageIndex: Number(s.stageIndex ?? s.index ?? s.id),
                     stageId: Number(s.id ?? s.stageId ?? s.stageIndex),
                     type: s.type || s.targetType || s.target
                 }));
-                const from = normalized.find(s => s.stageIndex === Number(fromStageIndex));
-                const to = normalized.find(s => s.stageIndex === Number(toStageIndex));
+                const from = refreshedNormalized.find(s => s.stageIndex === Number(fromStageIndex));
+                const to = refreshedNormalized.find(s => s.stageIndex === Number(toStageIndex));
 
                 const payload = {
                     clubId: Number(this.clubId),

frontend/src/components/tournament/TournamentResultsTab.vue

@@ -14,6 +14,27 @@
             <span v-if="liveMatchCount > 0" class="results-chip results-chip-live">{{ liveMatchCount }} {{ $t('tournaments.statusLive') }}</span>
             <span v-if="finishedMatchCount > 0" class="results-chip">{{ finishedMatchCount }} {{ $t('tournaments.statusFinished') }}</span>
         </div>
+        <div
+            v-if="(canStartKnockout && !showKnockout && numberOfGroupsForSelectedClass > 1) || (showKnockout && canResetKnockout && numberOfGroupsForSelectedClass > 1)"
+            class="results-primary-actions"
+        >
+            <button
+                v-if="canStartKnockout && !showKnockout && numberOfGroupsForSelectedClass > 1"
+                @click="$emit('start-knockout')"
+                class="btn-primary"
+                :disabled="knockoutOperationInProgress"
+            >
+                {{ $t('tournaments.startKORound') }}
+            </button>
+            <button
+                v-if="showKnockout && canResetKnockout && numberOfGroupsForSelectedClass > 1"
+                @click="$emit('reset-knockout')"
+                class="trash-btn"
+                :disabled="knockoutOperationInProgress"
+            >
+                🗑️ {{ $t('tournaments.deleteKORound') }}
+            </button>
+        </div>
         <div v-if="numberOfTables && (filteredGroupMatches.length || filteredKnockoutMatches.length)" class="distribute-tables-bar">
             <button @click="$emit('distribute-tables')" class="btn-primary">
                 {{ $t('tournaments.distributeTables') }}
@@ -646,6 +667,18 @@ export default {
     margin-bottom: 1rem;
 }
 
+.results-primary-actions {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 0.75rem;
+    align-items: center;
+    margin-bottom: 1rem;
+    padding: 0.9rem 1rem;
+    border: 1px solid var(--border-color);
+    border-radius: 12px;
+    background: var(--surface-color, #ffffff);
+}
+
 .results-chip {
     display: inline-flex;
     align-items: center;