refactor: rebuild SingleSelect and MultiSelect with Reka UI (#9742)

## Summary
- Rebuild `SingleSelect` with Reka UI Select primitives (SelectRoot,
SelectTrigger, SelectContent, SelectItem)
- Rebuild `MultiSelect` with Reka UI Popover + Listbox (PopoverRoot,
ListboxRoot with `multiple`)
- Remove PrimeVue dependency from both components
- Preserve existing API contract for all consumers

## TODO
- [x] Re-evaluate MultiSelect implementation (ComboboxRoot with
`multiple` may be cleaner than Popover+Listbox)
- [x] E2E verification in actual app (AssetFilterBar,
WorkflowTemplateSelectorDialog, etc.)

## Test plan
- [x] Storybook visual verification for all SingleSelect/MultiSelect
stories
- [x] Keyboard navigation (arrow keys, Enter, Escape, typeahead)
- [x] Multi-selection with badge count
- [x] Search filtering in MultiSelect
- [x] Clear all functionality
- [x] Disabled state
- [x] Invalid state (SingleSelect)
- [x] Loading state (SingleSelect)

## screenshot
<img width="519" height="475" alt="스크린샷 2026-03-20 오전 12 12 37"
src="https://github.com/user-attachments/assets/ffc7f0b0-c88c-486b-a253-73a4da73c1de"
/>
<img width="842" height="554" alt="스크린샷 2026-03-20 오전 12 23 51"
src="https://github.com/user-attachments/assets/410551d4-c843-4898-b305-13a6ad6978ca"
/>

## video


https://github.com/user-attachments/assets/2fc3a9b9-2671-4c2c-9f54-4f83598afb53



Fixes #9700

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9742-refactor-rebuild-SingleSelect-and-MultiSelect-with-Reka-UI-3206d73d36508113bee2cf160c8f2d50)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Alexander Brown <drjkl@comfy.org>

src/components/input/MultiSelect.test.ts

@@ -0,0 +1,60 @@
+import { mount } from '@vue/test-utils'
+import { describe, expect, it } from 'vitest'
+import { nextTick } from 'vue'
+import { createI18n } from 'vue-i18n'
+
+import MultiSelect from './MultiSelect.vue'
+
+const i18n = createI18n({
+  legacy: false,
+  locale: 'en',
+  messages: {
+    en: {
+      g: {
+        multiSelectDropdown: 'Multi-select dropdown',
+        noResultsFound: 'No results found',
+        search: 'Search',
+        clearAll: 'Clear all',
+        itemsSelected: 'Items selected'
+      }
+    }
+  }
+})
+
+describe('MultiSelect', () => {
+  function createWrapper() {
+    return mount(MultiSelect, {
+      attachTo: document.body,
+      global: {
+        plugins: [i18n]
+      },
+      props: {
+        modelValue: [],
+        label: 'Category',
+        options: [
+          { name: 'One', value: 'one' },
+          { name: 'Two', value: 'two' }
+        ]
+      }
+    })
+  }
+
+  it('keeps open-state border styling available while the dropdown is open', async () => {
+    const wrapper = createWrapper()
+
+    const trigger = wrapper.get('button[aria-haspopup="listbox"]')
+
+    expect(trigger.classes()).toContain(
+      'data-[state=open]:border-node-component-border'
+    )
+    expect(trigger.attributes('aria-expanded')).toBe('false')
+
+    await trigger.trigger('click')
+    await nextTick()
+
+    expect(trigger.attributes('aria-expanded')).toBe('true')
+    expect(trigger.attributes('data-state')).toBe('open')
+
+    wrapper.unmount()
+  })
+})