[feat] Replace NodeOptions with PrimeVue ContextMenu (#7114)

## Summary
- Add `NodeContextMenu.vue` using PrimeVue ContextMenu component with
native submenu support
- Rename `SubmenuPopover.vue` to `ColorPickerMenu.vue` (specialized for
color picker)
- Delete old components: `NodeOptions.vue`, `MenuOptionItem.vue`,
`useSubmenuPositioning.ts`
- Wire up context menu converter in `useMoreOptionsMenu.ts`
- Update tests to use hover instead of click for submenus

## Dependencies
**This PR depends on #7113** - the context menu converter infrastructure
PR. It should be merged after that PR.

## Benefits
- Native PrimeVue submenu support with proper keyboard navigation
- Constrained menu dimensions with overflow scrolling (max-h-[80vh])
- Cleaner component architecture with ~280 fewer lines of code
- Better separation: ColorPickerMenu handles only the custom color
picker UI

## Test plan
- [x] Typecheck passes
- [x] Lint passes
- [x] Knip passes
- [ ] Browser tests for submenu interactions pass
- [ ] Manual testing of node context menu

## Screenshots
(Menu UI should look the same, with improved submenu behavior)

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7114-feat-Replace-NodeOptions-with-PrimeVue-ContextMenu-2be6d73d365081fda576fd691175eacf)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>

src/components/graph/selectionToolbox/NodeOptionsButton.vue

@@ -1,6 +1,5 @@
 <template>
   <Button
-    ref="buttonRef"
     v-tooltip.top="{
       value: $t('g.moreOptions'),
       showDelay: 1000
@@ -17,17 +16,10 @@
 
 <script setup lang="ts">
 import Button from 'primevue/button'
-import { ref } from 'vue'
 
 import { toggleNodeOptions } from '@/composables/graph/useMoreOptionsMenu'
 
-const buttonRef = ref<InstanceType<typeof Button> | null>(null)
-
 const handleClick = (event: Event) => {
-  const el = (buttonRef.value as any)?.$el || buttonRef.value
-  const buttonEl = el instanceof HTMLElement ? el : null
-  if (buttonEl) {
-    toggleNodeOptions(event, buttonEl, true)
-  }
+  toggleNodeOptions(event)
 }
 </script>