feat(core+frontend): integrate mDNS-based network discovery and update UI

- **Network Discovery Service:**
  - Added platform-specific `DiscoveryModule` with JmDNS-based `JmDnsDiscoveryService` for JVM and no-op implementation for JS.
  - Implemented service and device discovery using mDNS to enable peer-to-peer synchronization within LAN.
  - Registered the module in Koin for dependency injection and integrated it with `networkModule`.

- **Frontend Integration:**
  - Enhanced `BewerbViewModel` with intents and actions for starting, stopping, and refreshing network scans.
  - Introduced polling for discovered services during an active scan.

- **UI Additions:**
  - Added a `NetworkDiscoveryPanel` in `TurnierBewerbeTab` to display discovered services and indicate scan state.
  - Updated action buttons to include toggle functionality for network scans.

frontend/core/network/build.gradle.kts

@@ -27,6 +27,7 @@ kotlin {
 
     jvmMain.dependencies {
       implementation(libs.ktor.client.cio)
+      implementation("org.jmdns:jmdns:3.5.5")
     }
 
     jsMain.dependencies {

frontend/core/network/src/commonMain/kotlin/at/mocode/frontend/core/network/NetworkModule.kt

@@ -7,8 +7,10 @@ import io.ktor.client.plugins.logging.*
 import io.ktor.client.request.*
 import io.ktor.serialization.kotlinx.json.*
 import kotlinx.serialization.json.Json
+import org.koin.core.module.Module
 import org.koin.core.qualifier.named
 import org.koin.dsl.module
+import at.mocode.frontend.core.network.discovery.discoveryModule
 
 /**
  * Schnittstelle zur Token-Bereitstellung – entkoppelt core-network von core-auth.
@@ -20,7 +22,8 @@ interface TokenProvider { fun getAccessToken(): String? }
  * - "baseHttpClient": Roh-Client für Auth/Keycloak (kein Token-Header)
  * - "apiClient":      Konfigurierter Client für das API-Gateway (Auth-Header, Retry, Timeout)
  */
-val networkModule = module {
+val networkModule: Module = module {
+  includes(discoveryModule)
 
   // 1. Basis-Client (für Auth-Endpunkte, ohne Bearer-Token)
   single(named("baseHttpClient")) {

frontend/core/network/src/commonMain/kotlin/at/mocode/frontend/core/network/discovery/DiscoveryModule.kt

@@ -0,0 +1,10 @@
+package at.mocode.frontend.core.network.discovery
+
+import org.koin.core.module.Module
+
+/**
+ * Erwartetes Koin-Modul für die Netzwerk-Discovery.
+ * Plattform-spezifische Implementierungen (JVM mit JmDNS, JS/Wasm evtl. No-op)
+ * müssen hier injiziert werden.
+ */
+expect val discoveryModule: Module

frontend/core/network/src/commonMain/kotlin/at/mocode/frontend/core/network/discovery/NetworkDiscoveryService.kt

@@ -0,0 +1,38 @@
+package at.mocode.frontend.core.network.discovery
+
+/**
+ * Modell für einen entdeckten Dienst im lokalen Netzwerk.
+ */
+data class DiscoveredService(
+    val name: String,
+    val host: String,
+    val port: Int,
+    val metadata: Map<String, String> = emptyMap()
+)
+
+/**
+ * Interface für die mDNS-basierte Entdeckung von Meldestelle-Instanzen.
+ * Erlaubt Offline-First Synchronisation im LAN.
+ */
+interface NetworkDiscoveryService {
+    /**
+     * Startet das Scannen nach verfügbaren Diensten im Netzwerk.
+     */
+    fun startDiscovery()
+
+    /**
+     * Stoppt den Scan-Vorgang.
+     */
+    fun stopDiscovery()
+
+    /**
+     * Registriert den eigenen Dienst, damit andere Instanzen ihn finden können.
+     * @param port Der Port, auf dem der lokale WebSocket-Server lauscht.
+     */
+    fun registerService(port: Int)
+
+    /**
+     * Gibt die Liste der aktuell entdeckten Dienste zurück.
+     */
+    fun getDiscoveredServices(): List<DiscoveredService>
+}

frontend/core/network/src/jsMain/kotlin/at/mocode/frontend/core/network/discovery/DiscoveryModule.kt

@@ -0,0 +1,18 @@
+package at.mocode.frontend.core.network.discovery
+
+import org.koin.core.module.Module
+import org.koin.dsl.module
+
+/**
+ * JS-spezifische Implementierung (vorerst No-op, da mDNS im Browser nicht nativ möglich).
+ */
+actual val discoveryModule: Module = module {
+    single<NetworkDiscoveryService> { NoOpDiscoveryService() }
+}
+
+class NoOpDiscoveryService : NetworkDiscoveryService {
+    override fun startDiscovery() {}
+    override fun stopDiscovery() {}
+    override fun registerService(port: Int) {}
+    override fun getDiscoveredServices(): List<DiscoveredService> = emptyList()
+}

frontend/core/network/src/jvmMain/kotlin/at/mocode/frontend/core/network/discovery/DiscoveryModule.kt

@@ -0,0 +1,11 @@
+package at.mocode.frontend.core.network.discovery
+
+import org.koin.core.module.Module
+import org.koin.dsl.module
+
+/**
+ * JVM-spezifische Implementierung des DiscoveryModules.
+ */
+actual val discoveryModule: Module = module {
+    single<NetworkDiscoveryService> { JmDnsDiscoveryService() }
+}

frontend/core/network/src/jvmMain/kotlin/at/mocode/frontend/core/network/discovery/JmDnsDiscoveryService.kt

@@ -0,0 +1,69 @@
+package at.mocode.frontend.core.network.discovery
+
+import javax.jmdns.JmDNS
+import javax.jmdns.ServiceEvent
+import javax.jmdns.ServiceInfo
+import javax.jmdns.ServiceListener
+import java.net.InetAddress
+import java.util.concurrent.ConcurrentHashMap
+
+/**
+ * JVM-spezifische Implementierung der Netzwerk-Discovery mittels JmDNS.
+ */
+class JmDnsDiscoveryService : NetworkDiscoveryService {
+
+    private var jmdns: JmDNS? = null
+    private val SERVICE_TYPE = "_meldestelle-biest._tcp.local."
+    private val discoveredServicesMap = ConcurrentHashMap<String, DiscoveredService>()
+
+    override fun startDiscovery() {
+        if (jmdns == null) {
+            jmdns = JmDNS.create(InetAddress.getLocalHost())
+        }
+
+        jmdns?.addServiceListener(SERVICE_TYPE, object : ServiceListener {
+            override fun serviceAdded(event: ServiceEvent) {
+                // Bei ServiceAdded fordern wir die Details an
+                jmdns?.requestServiceInfo(event.type, event.name)
+            }
+
+            override fun serviceRemoved(event: ServiceEvent) {
+                discoveredServicesMap.remove(event.name)
+                println("[Discovery] Service entfernt: ${event.name}")
+            }
+
+            override fun serviceResolved(event: ServiceEvent) {
+                val info = event.info
+                val service = DiscoveredService(
+                    name = event.name,
+                    host = info.inetAddresses.firstOrNull()?.hostAddress ?: "unknown",
+                    port = info.port,
+                    metadata = info.propertyNames.asSequence().associateWith { info.getPropertyString(it) }
+                )
+                discoveredServicesMap[event.name] = service
+                println("[Discovery] Service gefunden: ${service.name} @ ${service.host}:${service.port}")
+            }
+        })
+    }
+
+    override fun stopDiscovery() {
+        jmdns?.close()
+        jmdns = null
+        discoveredServicesMap.clear()
+    }
+
+    override fun registerService(port: Int) {
+        val serviceInfo = ServiceInfo.create(
+            SERVICE_TYPE,
+            "Meldestelle-${System.getProperty("user.name")}",
+            port,
+            "Offline-First Sync Node"
+        )
+        jmdns?.registerService(serviceInfo)
+        println("[Discovery] Eigenen Dienst registriert auf Port $port")
+    }
+
+    override fun getDiscoveredServices(): List<DiscoveredService> {
+        return discoveredServicesMap.values.toList()
+    }
+}