fix(frontend): design-review polish — table-compact height, header type-scale, tabs a11y

Fix 1 (A): move row height constraint from min-height on tbody tr
(CSS no-op on table-row) to height: 32px on td (works on table-cell).
Fix 2 (A): table header text-[11px] -> text-[12px] to align with
documented caption scale.
Fix 3: add aria-controls + id to Tabs buttons; wrap active tab content
in role="tabpanel" + aria-labelledby in EngagementDetailPage.
Test: add aria-controls/id assertion to Tabs.test.tsx (234 total).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/tests/components/Tabs.test.tsx

@@ -49,6 +49,16 @@ describe('Tabs', () => {
     expect(onChange).toHaveBeenCalledWith('description');
   });
 
+  it('sets aria-controls and id on each tab button', () => {
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={vi.fn()} />);
+    const schedBtn = screen.getByRole('tab', { name: /Schedule/i });
+    expect(schedBtn).toHaveAttribute('id', 'tab-schedule');
+    expect(schedBtn).toHaveAttribute('aria-controls', 'tabpanel-schedule');
+    const simsBtn = screen.getByRole('tab', { name: /Simulations/i });
+    expect(simsBtn).toHaveAttribute('id', 'tab-simulations');
+    expect(simsBtn).toHaveAttribute('aria-controls', 'tabpanel-simulations');
+  });
+
   it('has no rounded-md, transition-*, or shadow-* on tab buttons (brutalism)', () => {
     render(<Tabs items={ITEMS} activeId="schedule" onChange={vi.fn()} />);
     for (const btn of screen.getAllByRole('tab')) {