Refine settings IA with tabbed sections

Split Settings into tabbed sections while preserving draft state, improve mobile Settings nav/touch targets, and update dashboard UX coverage for the Codex tab.

scripts/dashboard-ux.ts

@@ -67,6 +67,7 @@ async function main() {
       baseUrl,
       async (page, state) => {
         await openSettings(page, baseUrl);
+        await openSettingsSection(page, 'settings-codex');
 
         const goalToggle = page.getByRole('checkbox', { name: /\/goal/ });
         await assertVisible(goalToggle);
@@ -236,6 +237,13 @@ async function openSettings(page: Page, baseUrl: string) {
   );
 }
 
+async function openSettingsSection(page: Page, targetId: string) {
+  await page
+    .locator(`.settings-nav button[data-settings-target="${targetId}"]`)
+    .click();
+  await assertVisible(page.locator(`#${targetId}`));
+}
+
 async function assertVisible(locator: ReturnType<Page['locator']>) {
   await locator.waitFor({ state: 'visible', timeout: 5_000 });
 }