feat(core+frontend): add P2P sync infrastructure with WebSocket support

- **Core Updates:**
  - Implemented `P2pSyncService` interface with platform-specific WebSocket implementations (`JvmP2pSyncService` and no-op for JS).
  - Developed `SyncEvent` sealed class hierarchy to handle peer synchronization events (e.g., `PingEvent`, `PongEvent`, `DataChangedEvent`, etc.).

- **Frontend Integration:**
  - Introduced `SyncManager` to manage peer discovery and synchronization, coupled with `NetworkDiscoveryService`.
  - Updated dependency injection to include `syncModule` for platform-specific sync service initialization.
  - Enhanced `BewerbViewModel` to support new sync capabilities, including observing sync events and UI updates for connected peers.

- **Backend Enhancements:**
  - Added ZNS-specific fields (`zns_nummer`, `zns_abteilung`) to Bewerb table for idempotent imports.
  - Introduced import ZNS logic to handle duplicates and align with SyncManager updates.

- **UI Improvements:**
  - Enhanced `TurnierBewerbeTab` with updated dialogs (ZNS imports, sync status) and dynamic previews.
  - Improved network syncing feedback and error handling in frontend components.

- **DB Changes:**
  - Added migration for new column fields in the Bewerb table with relevant indexing for ZNS import optimizations.

frontend/core/network/build.gradle.kts

@@ -21,13 +21,21 @@ kotlin {
       implementation(libs.ktor.client.serialization.kotlinx.json)
       implementation(libs.ktor.client.auth)
       implementation(libs.ktor.client.logging)
+      api(libs.ktor.client.websockets.common)
       implementation(libs.kotlinx.coroutines.core)
+      implementation(libs.kotlinx.datetime)
       api(libs.koin.core)
     }
 
     jvmMain.dependencies {
       implementation(libs.ktor.client.cio)
-      implementation("org.jmdns:jmdns:3.5.5")
+      implementation(libs.ktor.client.websockets)
+      implementation(libs.ktor.server.core)
+      implementation(libs.ktor.server.netty)
+      implementation(libs.ktor.server.websockets)
+      implementation(libs.ktor.server.contentNegotiation)
+      implementation(libs.ktor.server.serialization.kotlinx.json)
+      implementation(libs.jmdns)
     }
 
     jsMain.dependencies {