Refactor: Extract boilerplate: safeLaunchLoad, clearToast, ToastEffect (CODE-21/22/23) (#312)

- Extracted `safeLaunchLoad` inline extension function to `ViewModelExt.kt` to encapsulate API call success/failure handling logic and replaced usages across 18 viewmodels.
- Extracted `ToastHost` interface to standardize `clearToast()` behavior across all ViewModels displaying toasts.
- Extracted `ToastEffect` composable to `SharedComponents.kt` and applied it to 16 screens, reducing repetitive side effect code blocks.

Fixes #286

app/src/main/java/com/m57/hermescontrol/ui/system/SystemScreen.kt

@@ -1,6 +1,5 @@
 package com.m57.hermescontrol.ui.system
 
-import android.widget.Toast
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.FlowRow
@@ -26,7 +25,6 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
@@ -42,6 +40,7 @@ import com.m57.hermescontrol.ui.common.SectionHeader
 import com.m57.hermescontrol.ui.common.StatCard
 import com.m57.hermescontrol.ui.common.StatusBadge
 import com.m57.hermescontrol.ui.common.StatusBadgeType
+import com.m57.hermescontrol.ui.common.ToastEffect
 
 @OptIn(androidx.compose.foundation.layout.ExperimentalLayoutApi::class)
 @Composable
@@ -51,7 +50,6 @@ fun SystemScreen(
     viewModel: SystemViewModel = viewModel { SystemViewModel() },
 ) {
     val state by viewModel.uiState.collectAsStateWithLifecycle()
-    val context = LocalContext.current
     val spacing = LocalSpacing.current
     val statusColors = LocalHermesStatusColors.current
 
@@ -59,12 +57,7 @@ fun SystemScreen(
         viewModel.loadSystemData()
     }
 
-    LaunchedEffect(state.toastMessage) {
-        state.toastMessage?.let { msg ->
-            Toast.makeText(context, msg, Toast.LENGTH_SHORT).show()
-            viewModel.clearToast()
-        }
-    }
+    ToastEffect(toastMessage = state.toastMessage, onClearToast = viewModel::clearToast)
 
     HermesScaffold(
         title = { Text(stringResource(R.string.screen_system)) },

app/src/main/java/com/m57/hermescontrol/ui/system/SystemViewModel.kt

@@ -9,6 +9,8 @@ import com.m57.hermescontrol.data.model.SystemStatsResponse
 import com.m57.hermescontrol.data.remote.ApiClient
 import com.m57.hermescontrol.data.remote.NetworkResult
 import com.m57.hermescontrol.data.remote.safeApiCall
+import com.m57.hermescontrol.ui.common.ToastHost
+import com.m57.hermescontrol.ui.common.safeLaunchLoad
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -25,7 +27,7 @@ data class SystemUiState(
     val toastMessage: String? = null,
 )
 
-class SystemViewModel : ViewModel() {
+class SystemViewModel : ViewModel(), ToastHost {
     companion object {
         private const val TAG = "SystemViewModel"
     }
@@ -34,34 +36,28 @@ class SystemViewModel : ViewModel() {
     val uiState: StateFlow<SystemUiState> = _uiState.asStateFlow()
 
     fun loadSystemData() {
-        _uiState.update { it.copy(isLoading = true, errorMessage = null) }
-        viewModelScope.launch {
-            val result =
-                withContext(Dispatchers.IO) {
-                    safeApiCall { ApiClient.hermesApi.getSystemStats() }
+        safeLaunchLoad(
+            apiCall = { safeApiCall { ApiClient.hermesApi.getSystemStats() } },
+            onStart = { _uiState.update { it.copy(isLoading = true, errorMessage = null) } },
+            onSuccess = { data ->
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        stats = data,
+                    )
                 }
-            when (result) {
-                is NetworkResult.Success -> {
-                    _uiState.update {
-                        it.copy(
-                            isLoading = false,
-                            stats = result.data,
-                        )
-                    }
-                    // Doctor is optional; many servers do not expose it.
-                    loadDoctorReport()
+                // Doctor is optional; many servers do not expose it.
+                loadDoctorReport()
+            },
+            onError = { errorMsg ->
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        errorMessage = "Failed to load system stats: $errorMsg",
+                    )
                 }
-
-                is NetworkResult.Failure -> {
-                    _uiState.update {
-                        it.copy(
-                            isLoading = false,
-                            errorMessage = "Failed to load system stats: ${result.error.message}",
-                        )
-                    }
-                }
-            }
-        }
+            },
+        )
     }
 
     private fun loadDoctorReport() {
@@ -96,7 +92,7 @@ class SystemViewModel : ViewModel() {
         }
     }
 
-    fun clearToast() {
+    override fun clearToast() {
         _uiState.update { it.copy(toastMessage = null) }
     }
 }