fix: remove unused variables in test files

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/design-system/composites/Popover/Popover.test.tsx

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi } from 'vitest'
+import { describe, it, expect } from 'vitest'
 import { render, screen } from '@testing-library/react'
 import userEvent from '@testing-library/user-event'
 import { Popover } from './Popover'

src/design-system/primitives/ProgressBar/ProgressBar.test.tsx

@@ -63,13 +63,13 @@ describe('ProgressBar', () => {
   })
 
   it('applies sm size class to track', () => {
-    const { container } = render(<ProgressBar size="sm" value={50} />)
+    render(<ProgressBar size="sm" value={50} />)
     const track = screen.getByRole('progressbar')
     expect(track).toHaveClass('sm')
   })
 
   it('applies md size class to track by default', () => {
-    const { container } = render(<ProgressBar value={50} />)
+    render(<ProgressBar value={50} />)
     const track = screen.getByRole('progressbar')
     expect(track).toHaveClass('md')
   })