Add XCUITest suite with 27 test files covering unmapped P1 test cases

- Add 8 new test files: HeaderMoodLogging (TC-002), DayViewGrouping (TC-019),
  AllDayViewStyles (TC-021), MonthViewInteraction (TC-030), PaywallGate
  (TC-032/039/048), AppTheme (TC-070), IconPack (TC-072),
  PremiumCustomization (TC-075)
- Add accessibility IDs for paywall overlays, icon packs, app theme cards,
  and day view section headers
- Add --expire-trial launch argument to UITestMode for paywall gate testing
- Update QA test plan spreadsheet with XCUITest names for 14 test cases
- Include existing test infrastructure: screen objects, helpers, base class,
  and 19 previously written test files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Shared/Views/SettingsView/SettingsTabView.swift

@@ -34,6 +34,7 @@ struct SettingsTabView: View {
                 .frame(maxWidth: .infinity, alignment: .leading)
                 .padding(.horizontal, 16)
                 .padding(.top, 8)
+                .accessibilityIdentifier(AccessibilityID.Settings.header)
 
             // Upgrade Banner (only show if not subscribed)
             if !iapManager.isSubscribed && !iapManager.bypassSubscription {
@@ -123,6 +124,7 @@ struct UpgradeBannerView: View {
                                 .stroke(Color.accentColor, lineWidth: 1.5)
                         )
                 }
+                .accessibilityIdentifier(AccessibilityID.Settings.whyUpgradeButton)
 
                 // Subscribe button
                 Button {
@@ -138,6 +140,7 @@ struct UpgradeBannerView: View {
                                 .fill(Color.pink)
                         )
                 }
+                .accessibilityIdentifier(AccessibilityID.Settings.subscribeButton)
             }
         }
         .padding(14)
@@ -145,6 +148,7 @@ struct UpgradeBannerView: View {
             RoundedRectangle(cornerRadius: 14)
                 .fill(colorScheme == .dark ? Color(.systemGray6) : Color(.systemGray6).opacity(0.5))
         )
+        .accessibilityIdentifier(AccessibilityID.Settings.upgradeBanner)
     }
 }