feat(ui) : error toasts persist until dismissed, add progress bar on auto-dismiss toasts

frontend/app/composables/useToast.ts

@@ -7,6 +7,7 @@ export interface Toast {
   message: string
   type: ToastType
   visible: boolean
+  duration: number
 }
 
 const toasts = ref<Toast[]>([])
@@ -32,6 +33,7 @@ export function useToast() {
       message,
       type,
       visible: true,
+      duration: type === 'error' ? 0 : duration,
     }
 
     if (toasts.value.length >= MAX_TOASTS) {
@@ -40,10 +42,12 @@ export function useToast() {
 
     toasts.value.push(toast)
 
-    // Auto-remove after duration
-    setTimeout(() => {
-      removeToast(id)
-    }, duration)
+    // Only auto-dismiss non-error toasts
+    if (type !== 'error' && duration > 0) {
+      setTimeout(() => {
+        removeToast(id)
+      }, duration)
+    }
 
     return id
   }