feat(selectors-panel): add Used filter

src/__tests__/panels/selectorsPanel.test.tsx

@@ -266,6 +266,21 @@ describe('SelectorsPanel', () => {
     expect(within(panel).queryByRole('button', { name: /edit selector \.cta-button/i })).toBeNull()
   })
 
+  it('filters to only used selectors', () => {
+    loadSiteWithSelectors()
+    render(<SelectorsPanel variant="docked" />)
+
+    const panel = screen.getByTestId('selectors-panel')
+    fireEvent.click(within(panel).getByRole('button', { name: /^used$/i }))
+
+    // hero-title and cta-button are referenced by page nodes; unused-card and
+    // text-m have no nodes referencing them.
+    expect(within(panel).getByRole('button', { name: /edit selector \.hero-title/i })).toBeDefined()
+    expect(within(panel).getByRole('button', { name: /edit selector \.cta-button/i })).toBeDefined()
+    expect(within(panel).queryByRole('button', { name: /edit selector \.unused-card/i })).toBeNull()
+    expect(within(panel).queryByRole('button', { name: /edit selector \.text-m/i })).toBeNull()
+  })
+
   it('searches selector property names and values, not just names', () => {
     loadSiteWithSelectors()
     render(<SelectorsPanel variant="docked" />)

src/admin/pages/site/panels/SelectorsPanel/SelectorsPanel.tsx

@@ -37,7 +37,7 @@ interface SelectorsPanelProps {
   variant?: 'docked'
 }
 
-type SelectorFilter = 'all' | 'user' | 'utility' | 'unused'
+type SelectorFilter = 'all' | 'user' | 'utility' | 'used' | 'unused'
 
 /**
  * How many selector rows to mount per batch. A generated framework (e.g. the
@@ -55,6 +55,7 @@ const SELECTOR_FILTER_ITEMS: FilterBarItem<SelectorFilter>[] = [
   { value: 'all', label: 'All' },
   { value: 'user', label: 'User' },
   { value: 'utility', label: 'Utility' },
+  { value: 'used', label: 'Used' },
   { value: 'unused', label: 'Unused' },
 ]
 
@@ -77,6 +78,7 @@ function getEmptyFilterMessage(filter: SelectorFilter, query: string): string {
   if (normalized) return `No selectors match “${normalized}”.`
   if (filter === 'user') return 'No user selectors yet.'
   if (filter === 'utility') return 'No utility selectors yet.'
+  if (filter === 'used') return 'No used selectors yet.'
   if (filter === 'unused') return 'No unused selectors — every selector is in use.'
   return 'No selectors match the current filters.'
 }
@@ -136,6 +138,8 @@ export function SelectorsPanel({ variant = 'docked' }: SelectorsPanelProps) {
   const filteredClasses = reusableClasses.filter((cls) => {
     if (filter === 'user' && isGeneratedClass(cls)) return false
     if (filter === 'utility' && !isGeneratedClass(cls)) return false
+    if (filter === 'used' && resolveSelectorUsage(cls, usageMap, classTokenUsage).unused)
+      return false
     if (filter === 'unused' && !resolveSelectorUsage(cls, usageMap, classTokenUsage).unused)
       return false
     // Search matches the selector name AND its declared CSS (property names and