fix(discovery): ensure map icon is visible on session detail

- Load nodes in DiscoveryHistoryDetailViewModel so the UI can check for mappable data
- Update DiscoveryHistoryDetailScreen to show the Map icon if either the session or any discovered nodes have coordinates
- Pass loaded nodes to PresetResultCard for proper display in the history detail view

Author: jamesarich

feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/DiscoveryHistoryDetailViewModel.kt

@@ -18,23 +18,45 @@ package org.meshtastic.feature.discovery
 
 import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
 import org.koin.core.annotation.InjectedParam
 import org.koin.core.annotation.KoinViewModel
 import org.meshtastic.core.database.dao.DiscoveryDao
+import org.meshtastic.core.database.entity.DiscoveredNodeEntity
 import org.meshtastic.core.database.entity.DiscoveryPresetResultEntity
 import org.meshtastic.core.database.entity.DiscoverySessionEntity
+import org.meshtastic.core.ui.viewmodel.safeLaunch
 import org.meshtastic.core.ui.viewmodel.stateInWhileSubscribed
 
 @KoinViewModel
 class DiscoveryHistoryDetailViewModel(
     @InjectedParam private val sessionId: Long,
-    discoveryDao: DiscoveryDao,
+    private val discoveryDao: DiscoveryDao,
 ) : ViewModel() {
 
     val session: StateFlow<DiscoverySessionEntity?> =
         discoveryDao.getSessionFlow(sessionId).stateInWhileSubscribed(initialValue = null)
 
     val presetResults: StateFlow<List<DiscoveryPresetResultEntity>> =
         discoveryDao.getPresetResultsFlow(sessionId).stateInWhileSubscribed(initialValue = emptyList())
+
+    private val _nodesByPreset = MutableStateFlow<Map<Long, List<DiscoveredNodeEntity>>>(emptyMap())
+    val nodesByPreset: StateFlow<Map<Long, List<DiscoveredNodeEntity>>> = _nodesByPreset.asStateFlow()
+
+    init {
+        loadNodes()
+    }
+
+    private fun loadNodes() {
+        safeLaunch(tag = "loadNodes") {
+            val results = discoveryDao.getPresetResults(sessionId)
+            val nodesMap = mutableMapOf<Long, List<DiscoveredNodeEntity>>()
+            for (result in results) {
+                nodesMap[result.id] = discoveryDao.getDiscoveredNodes(result.id)
+            }
+            _nodesByPreset.value = nodesMap
+        }
+    }
 }

feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/ui/DiscoveryHistoryDetailScreen.kt

@@ -58,6 +58,7 @@ fun DiscoveryHistoryDetailScreen(
 ) {
     val session by viewModel.session.collectAsStateWithLifecycle()
     val presetResults by viewModel.presetResults.collectAsStateWithLifecycle()
+    val nodesByPreset by viewModel.nodesByPreset.collectAsStateWithLifecycle()
 
     Scaffold(
         topBar = {
@@ -68,7 +69,8 @@ fun DiscoveryHistoryDetailScreen(
                 },
                 actions = {
                     val s = session
-                    if (s != null && s.userLatitude != 0.0 && s.userLongitude != 0.0) {
+                    val hasAnyMappableNodes = nodesByPreset.values.flatten().any { it.latitude != null && it.longitude != null && it.latitude != 0.0 }
+                    if (s != null && (s.userLatitude != 0.0 || hasAnyMappableNodes)) {
                         IconButton(onClick = { onNavigateToMap(s.id) }) {
                             Icon(MeshtasticIcons.Map, contentDescription = "View map")
                         }
@@ -85,7 +87,12 @@ fun DiscoveryHistoryDetailScreen(
 
             if (presetResults.isNotEmpty()) {
                 Text(text = "Preset Results", style = MaterialTheme.typography.titleMedium)
-                presetResults.forEach { result -> PresetResultCard(result = result, nodes = emptyList()) }
+                presetResults.forEach { result ->
+                    PresetResultCard(
+                        result = result,
+                        nodes = nodesByPreset[result.id].orEmpty(),
+                    )
+                }
             }
         }
     }