fix: App mode - Widget dropdowns clipped in sidebar (#10338)

## Summary

Popover components for graph mode are appendTo self so scale/translate
works, however in the sidebar this causes them to be clipped by the
parent overflow. This adds a provide/inject flag to change these to be
appended to the body.

## Changes

- **What**: 
- add append to injection for overriding where popovers are mounted
- ensure dropdowns respect this flag
- extract enterAppModeWithInputs helper
- tests

Before:  
<img width="225" height="140" alt="image"
src="https://github.com/user-attachments/assets/bd83b0cd-49a9-45dd-8344-4c10221444fc"
/>

After:  
<img width="238" height="225" alt="image"
src="https://github.com/user-attachments/assets/286e28e9-b37d-4ffc-91a9-7c340757d3fc"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10338-fix-App-mode-Widget-dropdowns-clipped-in-sidebar-3296d73d365081e2ba38e3e82006d65e)
by [Unito](https://www.unito.io)

src/components/builder/AppModeWidgetList.vue

@@ -6,6 +6,7 @@ import { useI18n } from 'vue-i18n'
 import Popover from '@/components/ui/Popover.vue'
 import Button from '@/components/ui/button/Button.vue'
 import { extractVueNodeData } from '@/composables/graph/useGraphNodeManager'
+import { OverlayAppendToKey } from '@/composables/useTransformCompatOverlayProps'
 import { isPromotedWidgetView } from '@/core/graph/subgraph/promotedWidgetTypes'
 import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import { LGraphEventMode } from '@/lib/litegraph/src/types/globalEnums'
@@ -44,6 +45,7 @@ const appModeStore = useAppModeStore()
 const maskEditor = useMaskEditor()
 
 provide(HideLayoutFieldKey, true)
+provide(OverlayAppendToKey, 'body')
 
 const graphNodes = shallowRef<LGraphNode[]>(app.rootGraph.nodes)
 useEventListener(