feat(core+frontend): enhance SyncEvent model and integrate sync handling in BewerbViewModel

- **Core Updates:**
  - Expanded `SyncEvent` model with additional fields (`eventId`, `sequenceNumber`, `originNodeId`, `createdAt`, `checksum`, `schemaVersion`) for improved event tracking and validation.
  - Updated event classes (`PingEvent`, `PongEvent`, `DataChangedEvent`, `DataRequestEvent`) to align with the extended `SyncEvent`.

- **Frontend Enhancements:**
  - Enhanced `BewerbViewModel` to handle sync events (`PingEvent`, `DataChangedEvent`) and observe connected peers using `SyncManager`.
  - Added support for

frontend/features/turnier-feature/src/commonMain/kotlin/at/mocode/turnier/feature/presentation/BewerbViewModel.kt

@@ -2,6 +2,7 @@ package at.mocode.turnier.feature.presentation
 
 import at.mocode.frontend.core.network.discovery.DiscoveredService
 import at.mocode.frontend.core.network.sync.SyncManager
+import at.mocode.frontend.core.network.sync.*
 import at.mocode.turnier.feature.domain.Bewerb
 import at.mocode.turnier.feature.domain.BewerbRepository
 import at.mocode.turnier.feature.domain.StartlistenRepository
@@ -93,8 +94,30 @@ class BewerbViewModel(
 
   private fun observeSyncEvents() {
     syncManager?.let { manager ->
-      // In einer realen App würde das P2pSyncService.incomingEvents Flow genutzt
-      // Hier als Demo-Verknüpfung
+      scope.launch {
+        manager.getIncomingEvents().collect { event ->
+          when (event) {
+            is DataChangedEvent -> {
+              if (event.aggregateType == "Bewerb" || event.aggregateType == "Startliste") {
+                load() // Bei relevanten Änderungen neu laden
+              }
+            }
+            is PingEvent -> {
+              // Optional: Heartbeat loggen oder Status anzeigen
+            }
+            else -> {}
+          }
+        }
+      }
+
+      // Auch verbundene Peers beobachten
+      scope.launch {
+        manager.getConnectedPeers().collect { peers ->
+          reduce { it.copy(discoveredNodes = peers.map { p ->
+              at.mocode.frontend.core.network.discovery.DiscoveredService("P2P", p, 0)
+          }) }
+        }
+      }
     }
   }
 
@@ -143,6 +166,13 @@ class BewerbViewModel(
   private fun startScan() {
     syncManager?.start(8080)
     _state.update { it.copy(isScanning = true) }
+    // Nach dem Start des Servers ein Ping-Event broadcasten um Präsenz zu zeigen
+    syncManager?.broadcastEvent(PingEvent(
+      eventId = turnierId.toString(),
+      sequenceNumber = 0,
+      originNodeId = "Client-${(1000..9999).random()}",
+      createdAt = 0 // In commonMain ohne Clock-Lib erst mal 0
+    ))
     refreshNodes()
   }