feat(common): add ConfirmDialog and safeLaunchAction helper

Add reusable ConfirmDialog with destructive action styling.
Add safeLaunchAction to ViewModelExt for mutating calls with unit tests.

app/src/test/java/com/m57/hermescontrol/ui/common/ViewModelExtTest.kt

@@ -0,0 +1,74 @@
+package com.m57.hermescontrol.ui.common
+
+import androidx.lifecycle.ViewModel
+import com.m57.hermescontrol.data.remote.NetworkError
+import com.m57.hermescontrol.data.remote.NetworkResult
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.test.setMain
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class ViewModelExtTest {
+    private val testDispatcher = StandardTestDispatcher()
+
+    @Before
+    fun setUp() {
+        Dispatchers.setMain(testDispatcher)
+    }
+
+    @After
+    fun tearDown() {
+        Dispatchers.resetMain()
+    }
+
+    private class TestViewModel : ViewModel()
+
+    @Test
+    fun `safeLaunchAction triggers onStart, onSuccess and onComplete on success`() =
+        runTest(testDispatcher) {
+            val vm = TestViewModel()
+            var started = false
+            var successResult: String? = null
+            var completed = false
+
+            vm.safeLaunchAction(
+                onStart = { started = true },
+                apiCall = { NetworkResult.Success("ok") },
+                onSuccess = { successResult = it },
+                onError = {},
+                onComplete = { completed = true },
+            )
+
+            assertTrue(started)
+            testDispatcher.scheduler.advanceUntilIdle()
+            assertEquals("ok", successResult)
+            assertTrue(completed)
+        }
+
+    @Test
+    fun `safeLaunchAction triggers onError and onComplete on failure`() =
+        runTest(testDispatcher) {
+            val vm = TestViewModel()
+            var errorMessage: String? = null
+            var completed = false
+
+            vm.safeLaunchAction(
+                apiCall = { NetworkResult.Failure(NetworkError.Unknown("network error", Exception("boom"))) },
+                onSuccess = {},
+                onError = { errorMessage = it },
+                onComplete = { completed = true },
+            )
+
+            testDispatcher.scheduler.advanceUntilIdle()
+            assertEquals("network error", errorMessage)
+            assertTrue(completed)
+        }
+}