feat: unify search components by replacing SearchBox/SearchBoxV2 with SearchInput (#9644)

## Summary

Replace legacy `SearchBox` (PrimeVue) and `SearchBoxV2` with the unified
`SearchInput` (reka-ui) component across all consumers.

## Changes

- **What**: Remove `SearchBox.vue`, `SearchBoxV2.vue`, their tests and
stories. Migrate all 14 consumers to `SearchInput`. Move layout classes
to `ComboboxRoot` for proper flex sizing. Extract filter button/chips in
`NodeLibrarySidebarTab`. Standardize modal search width to `flex-1
max-w-lg`.
- **Dependencies**: None new — `SearchInput` already existed using
reka-ui

## Review Focus

- `NodeLibrarySidebarTab.vue`: filter button and `SearchFilterChip`
rendering moved outside the search component
- `SearchInput.vue`: `className` now applied to `ComboboxRoot` instead
of `ComboboxAnchor` for correct flex layout
- Modal dialogs (`WorkflowTemplateSelectorDialog`, `AssetBrowserModal`,
`SampleModelSelector`) unified to `flex-1 max-w-lg`

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9644-feat-unify-search-components-by-replacing-SearchBox-SearchBoxV2-with-SearchInput-31e6d73d365081ebac55cb265f33b631)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: github-actions <github-actions@github.com>

src/components/sidebar/tabs/NodeLibrarySidebarTabV2.test.ts

@@ -69,7 +69,7 @@ vi.mock('./nodeLibrary/NodeDragPreview.vue', () => ({
   }
 }))
 
-vi.mock('@/components/common/SearchBoxV2.vue', () => ({
+vi.mock('@/components/ui/search-input/SearchInput.vue', () => ({
   default: {
     name: 'SearchBox',
     template: '<input data-testid="search-box" />',