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/EmptyView.swift

@@ -34,10 +34,12 @@ struct EmptyHomeView: View {
                             .padding()
                             .fixedSize(horizontal: false, vertical: true)
                             .foregroundColor(textColor)
+                            .accessibilityIdentifier(AccessibilityID.DayView.emptyStateNoData)
                         Spacer()
                     }
                 }
             }
+            .accessibilityIdentifier(AccessibilityID.DayView.emptyState)
         }
         .fixedSize(horizontal: false, vertical: true)
         .cornerRadius(Constants.viewsCornerRaidus, corners: [.topLeft, .topRight, .bottomLeft, .bottomRight])