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/sessions/SessionsViewModel.kt

@@ -1,18 +1,14 @@
 package com.m57.hermescontrol.ui.sessions
 
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.viewModelScope
 import com.m57.hermescontrol.data.model.SessionInfo
 import com.m57.hermescontrol.data.remote.ApiClient
-import com.m57.hermescontrol.data.remote.NetworkResult
 import com.m57.hermescontrol.data.remote.safeApiCall
-import kotlinx.coroutines.Dispatchers
+import com.m57.hermescontrol.ui.common.safeLaunchLoad
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.update
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
 
 data class SessionsUiState(
     val isLoading: Boolean = false,
@@ -25,31 +21,25 @@ class SessionsViewModel : ViewModel() {
     val uiState: StateFlow<SessionsUiState> = _uiState.asStateFlow()
 
     fun loadSessions() {
-        _uiState.update { it.copy(isLoading = true, errorMessage = null) }
-        viewModelScope.launch {
-            val result =
-                withContext(Dispatchers.IO) {
-                    safeApiCall { ApiClient.hermesApi.getSessions() }
+        safeLaunchLoad(
+            apiCall = { safeApiCall { ApiClient.hermesApi.getSessions() } },
+            onStart = { _uiState.update { it.copy(isLoading = true, errorMessage = null) } },
+            onSuccess = { data ->
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        sessions = data?.sessions.orEmpty(),
+                    )
                 }
-            when (result) {
-                is NetworkResult.Success -> {
-                    _uiState.update {
-                        it.copy(
-                            isLoading = false,
-                            sessions = result.data?.sessions.orEmpty(),
-                        )
-                    }
+            },
+            onError = { errorMsg ->
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        errorMessage = "Failed to load sessions: $errorMsg",
+                    )
                 }
-
-                is NetworkResult.Failure -> {
-                    _uiState.update {
-                        it.copy(
-                            isLoading = false,
-                            errorMessage = "Failed to load sessions: ${result.error.message}",
-                        )
-                    }
-                }
-            }
-        }
+            },
+        )
     }
 }