feat(settings): search across all settings (#463)

A search box at the top of the settings sidebar (Ctrl/Cmd+F while settings
are open). Results replace the page list while typing, showing the page and
section; picking one (or Enter for the top result) opens that page, scrolls
to the setting and briefly outlines it. Esc clears.

The index is built from the settings source itself (SettingTile titles and
descriptions, section headers), loaded as raw text in a lazy chunk on first
search, so options added later are found without a hand-kept list.
Desktop-only options only show in the desktop app.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

e2e/settings-search.spec.ts

@@ -0,0 +1,51 @@
+import { test, expect } from '@playwright/test';
+import { ensureUser, hsReachable, loginUI, uniq } from './localHs';
+
+// [Gitea #463] Search across all settings.
+test.describe('settings search (#463)', () => {
+  test.beforeAll(async () => {
+    test.skip(!(await hsReachable()), 'local homeserver not running');
+  });
+
+  test('finds a setting, opens its page and shows it', async ({ page }) => {
+    test.setTimeout(120_000);
+    const user = await ensureUser(uniq('ss'));
+    await loginUI(page, user);
+    await page.getByRole('button', { name: 'User Settings' }).click();
+    const dialog = page.getByRole('dialog').first();
+    const box = dialog.getByRole('textbox', { name: 'Search settings' });
+
+    // Ctrl+F focuses the box while settings are open (after the dialog has
+    // placed its own initial focus).
+    await expect(box).toBeVisible();
+    await page.waitForTimeout(800);
+    await page.keyboard.press('ControlOrMeta+f');
+    await expect(box).toBeFocused();
+
+    await box.fill('deafen');
+    const results = dialog.getByRole('list', { name: 'Matching settings' });
+    const first = results.getByRole('listitem').first();
+    await expect(first).toContainText('Push to deafen');
+    await expect(first).toContainText('Calls & audio');
+    await expect(dialog.getByRole('navigation', { name: 'Settings sections' })).toBeHidden();
+    await first.click();
+    await expect(dialog.getByText('Calls & audio', { exact: true }).last()).toBeVisible();
+    await expect(dialog.getByText('Push to deafen', { exact: true })).toBeInViewport();
+    await expect(dialog.getByRole('navigation', { name: 'Settings sections' })).toBeVisible();
+
+    // A description word finds it too; Enter picks the top result.
+    await box.fill('utm');
+    await expect(results.getByRole('listitem').first()).toContainText(
+      'Strip tracking parameters from links',
+    );
+    await box.press('Enter');
+    await expect(dialog.getByText('Strip tracking parameters from links')).toBeInViewport();
+
+    // No match, then Esc clears.
+    await box.fill('zzzz-nothing');
+    await expect(dialog.getByText(/No settings match/)).toBeVisible();
+    await box.press('Escape');
+    await expect(box).toHaveValue('');
+    await expect(dialog).toBeVisible();
+  });
+});