fix: prevent duplicate node search filters (#8935)

## Summary

- Add duplicate check in `addFilter` to prevent identical filter chips
(same `filterDef.id` and `value`) from being added to the node search
box

## Related Issue

- Fixes https://github.com/Comfy-Org/ComfyUI_frontend/issues/3559

## Changes

- `NodeSearchBoxPopover.vue`: Guard `addFilter` with `isDuplicate` check
comparing `filterDef.id` and `value`
- `NodeSearchBoxPopover.test.ts`: Add unit tests covering duplicate
prevention, distinct id, and distinct value cases

## QA

- [x] `pnpm typecheck` passes
- [x] `pnpm lint` passes
- [x] `pnpm format:check` passes
- [x] Unit tests pass (4/4)
- [x] Bug reproduced with Playwright before fix

### as-is
<img width="719" height="269" alt="스크린샷 2026-02-17 오후 5 45 48"
src="https://github.com/user-attachments/assets/403bf53a-53dd-4257-945f-322717f304b3"
/>

### to-be
<img width="765" height="291" alt="스크린샷 2026-02-17 오후 5 44 25"
src="https://github.com/user-attachments/assets/7995b15e-d071-4955-b054-5e0ca7c5c5bf"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8935-fix-prevent-duplicate-node-search-filters-30a6d73d3650816797cfcc524228f270)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

browser_tests/tests/nodeSearchBox.spec.ts

@@ -215,6 +215,14 @@ test.describe('Node search box', { tag: '@node' }, () => {
       await expectFilterChips(comfyPage, ['MODEL', 'CLIP'])
     })
 
+    test('Does not add duplicate filter with same type and value', async ({
+      comfyPage
+    }) => {
+      await comfyPage.searchBox.addFilter('MODEL', 'Input Type')
+      await comfyPage.searchBox.addFilter('MODEL', 'Input Type')
+      await expectFilterChips(comfyPage, ['MODEL'])
+    })
+
     test('Can remove filter', async ({ comfyPage }) => {
       await comfyPage.searchBox.addFilter('MODEL', 'Input Type')
       await comfyPage.searchBox.removeFilter(0)