fix(workspace-cleanup): make the filter panel scrollable

The height cap sat on the ScrollArea Root, but the Radix viewport inside is
h-full — under an indefinite root height that collapses to auto, so the
viewport grew to full content height with nothing to scroll while the root
clipped at 420px. The last facet groups (Archived, and the tail of Workspace
status) were unreachable behind the footer.

Move the cap to the viewport, which is what the ScrollArea wrapper's
viewportClassName exists for. Adds a regression test that pins the cap to the
viewport; it fails against the previous markup.

src/renderer/src/components/workspace-cleanup/workspace-cleanup-filter-bar.test.tsx

@@ -6,39 +6,55 @@ import { WorkspaceCleanupFilterBar } from './workspace-cleanup-filter-bar'
 
 afterEach(cleanup)
 
+function renderFilterBar(facetPanelOpen = false): void {
+  render(
+    <WorkspaceCleanupFilterBar
+      facetProps={{
+        filters: createDefaultWorkspaceCleanupFilterState(),
+        counts: {
+          activity: 0,
+          size: 0,
+          status: 0,
+          agent: 0,
+          git: 0,
+          review: 0,
+          ticket: 0,
+          context: 0,
+          location: 0,
+          safety: 0
+        },
+        totalCount: 100,
+        options: { workspaceStatuses: [], hostIds: [], repos: [], reviewProviders: [] },
+        onPatch: vi.fn()
+      }}
+      facetPanelOpen={facetPanelOpen}
+      onFacetPanelOpenChange={vi.fn()}
+      activeFacetGroupCount={0}
+      matchedCount={100}
+      hasActiveFilters={false}
+      gitEvidence={{ pendingCount: 0, totalCount: 0 }}
+      onQueryChange={vi.fn()}
+      onClearFilters={vi.fn()}
+    />
+  )
+}
+
 describe('WorkspaceCleanupFilterBar', () => {
   it('keeps size measurement out of the browse controls', () => {
-    render(
-      <WorkspaceCleanupFilterBar
-        facetProps={{
-          filters: createDefaultWorkspaceCleanupFilterState(),
-          counts: {
-            activity: 0,
-            size: 0,
-            status: 0,
-            agent: 0,
-            git: 0,
-            review: 0,
-            ticket: 0,
-            context: 0,
-            location: 0,
-            safety: 0
-          },
-          totalCount: 100,
-          options: { workspaceStatuses: [], hostIds: [], repos: [], reviewProviders: [] },
-          onPatch: vi.fn()
-        }}
-        facetPanelOpen={false}
-        onFacetPanelOpenChange={vi.fn()}
-        activeFacetGroupCount={0}
-        matchedCount={100}
-        hasActiveFilters={false}
-        gitEvidence={{ pendingCount: 0, totalCount: 0 }}
-        onQueryChange={vi.fn()}
-        onClearFilters={vi.fn()}
-      />
-    )
+    renderFilterBar()
 
     expect(screen.queryByRole('button', { name: 'Scan' })).toBeNull()
   })
+
+  it('caps the facet panel height on the scroll viewport so it stays scrollable', () => {
+    renderFilterBar(true)
+
+    // Why: on the ScrollArea Root the cap only clips — the h-full viewport
+    // collapses under an indefinite height and the last facet groups become
+    // unreachable behind the footer.
+    const viewport = document.querySelector('[data-slot="scroll-area-viewport"]')
+    const root = document.querySelector('[data-slot="scroll-area"]')
+    expect(viewport?.className).toContain('max-h-[420px]')
+    expect(root?.className).not.toContain('max-h-')
+  })
 })

src/renderer/src/components/workspace-cleanup/workspace-cleanup-filter-bar.tsx

@@ -68,7 +68,11 @@ export function WorkspaceCleanupFilterBar({
           </Button>
         </PopoverTrigger>
         <PopoverContent align="end" sideOffset={6} className="w-[320px] p-0">
-          <ScrollArea className="max-h-[420px]">
+          {/* Why: the cap must sit on the scroll viewport. On the Root it only
+              clips — the viewport is h-full, which collapses to auto under an
+              indefinite height, so the panel grew past the cap unscrollably and
+              hid the last facet groups behind the footer. */}
+          <ScrollArea viewportClassName="max-h-[420px]">
             <WorkspaceCleanupLifecycleFacets {...facetProps} />
             <WorkspaceCleanupGitReviewFacets {...facetProps} />
           </ScrollArea>