feat(ui) : create useUnsavedGuard composable for edit page navigation protection

frontend/app/composables/useUnsavedGuard.ts

@@ -0,0 +1,32 @@
+import type { Ref } from 'vue'
+
+export function useUnsavedGuard(isDirty: Ref<boolean>) {
+  const { confirm } = useConfirm()
+
+  function handleBeforeUnload(e: BeforeUnloadEvent) {
+    if (isDirty.value) {
+      e.preventDefault()
+      e.returnValue = ''
+    }
+  }
+
+  onMounted(() => {
+    window.addEventListener('beforeunload', handleBeforeUnload)
+  })
+
+  onUnmounted(() => {
+    window.removeEventListener('beforeunload', handleBeforeUnload)
+  })
+
+  onBeforeRouteLeave(async () => {
+    if (!isDirty.value) return true
+    const ok = await confirm({
+      title: 'Modifications non sauvegardées',
+      message: 'Vous avez des modifications en cours. Voulez-vous quitter sans sauvegarder ?',
+      confirmText: 'Quitter sans sauver',
+      cancelText: 'Rester',
+      dangerous: true,
+    })
+    return ok
+  })
+}