test(visual): expand snapshot coverage for member-area pages

Adds 13 new visual regression baselines:
- Public: about (desktop + mobile), members (desktop + mobile)
- Authenticated desktop: member-account, member-activity, connections,
  admin-dashboard, members-detail
- Authenticated mobile: member-dashboard, member-profile,
  member-account, connections

Switches to a single serial test.describe with a beforeAll that logs in
once and saves the auth cookie via storageState. This avoids repeated
/api/dev/test-login calls that exhausted the dev server's MongoDB
connections under parallel execution.

Masks added: .tl-time, .stat-val, .item-date, .mc-avatar, .cc-avatar,
.profile-avatar, .filter-count — covering activity timestamps, stat
values, member join dates, avatars, and member counts.

.gitignore

@@ -29,6 +29,7 @@ scripts/*.js
 # Playwright
 e2e/test-results/
 playwright-report/
+e2e/.auth/
 
 # Worktrees
 .worktrees/