feat(ui): keep the active operations tab across page refreshes (#27)

Persist the selected tab ID to localStorage (sw-active-tab) on every change
and restore it on mount when it matches one of the seven valid tab IDs. The
Radix Tabs become controlled for this; SSR and first client render still agree
on the default, so there is no hydration mismatch.

e2e/smoke.spec.ts

@@ -70,6 +70,18 @@ test('tabs switch panels client-side (event log terminal)', async ({ page }) =>
   await expect(page.getByText(/T\d+ \/\/ /).first()).toBeVisible();
 });
 
+test('active tab survives a page reload (#27)', async ({ page }) => {
+  await page.goto('/');
+  // Fresh context → nothing stored yet, so CREW starts unselected (the default is WORLD MAP).
+  await expect(page.getByRole('tab', { name: 'CREW' })).toHaveAttribute('aria-selected', 'false');
+  await page.getByRole('tab', { name: 'CREW' }).click();
+  await expect(page.getByRole('tab', { name: 'CREW' })).toHaveAttribute('aria-selected', 'true');
+
+  await page.reload();
+  // The tab is restored from localStorage on mount — no API state involved, so this holds across retries.
+  await expect(page.getByRole('tab', { name: 'CREW' })).toHaveAttribute('aria-selected', 'true');
+});
+
 test('world map shows the generated starting system and its neighbours', async ({ page }) => {
   const world = (await (await page.request.get('/api/world')).json()) as WorldState;