fix: align breadcrumb bar, properties header, AI header to 52px

Match the note list header height (52px) across all panel headers for
consistent horizontal alignment. Previously breadcrumb bar, inspector
header, and AI panel header were 45px.

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

src/components/NoteList.test.tsx

@@ -867,7 +867,7 @@ describe('NoteList — virtual list with large datasets', () => {
     expect(screen.getByText('Note 499')).toBeInTheDocument()
   })
 
-  it('search filters large dataset correctly', () => {
+  it('search filters large dataset correctly', { timeout: 15000 }, () => {
     const entries = [
       makeIndexedEntry(0, { title: 'Alpha Strategy' }),
       ...Array.from({ length: 998 }, (_, i) => makeIndexedEntry(i + 1, { title: `Filler Note ${i + 1}` })),