fix(test): raise mobile-audit timeout to 30min for 4-viewport runs

Task 24 audit run hit the 10-minute test.setTimeout ceiling after capturing
2 of 4 viewport passes (iphone-se complete, iphone-16 complete-ish, 16-pro
partial, pro-max not started). 4 viewports × ~45 routes × slowMo: 200 needs
more headroom than 600s gave. 30min is comfortable headroom; the per-test
project timeout is matched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/e2e/audit/mobile.spec.ts

@@ -340,7 +340,7 @@ async function writeIndex(allByViewport: Map<string, Capture[]>): Promise<void>
 }
 
 test('mobile audit — every page at iPhone viewports', async ({ browser, request }) => {
-  test.setTimeout(600_000);
+  test.setTimeout(1_800_000);
 
   await fs.mkdir(OUT_ROOT, { recursive: true });
   await ensureAdminExists(request);