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>

Tests iOS/MonthViewTests.swift

@@ -0,0 +1,49 @@
+//
+//  MonthViewTests.swift
+//  Tests iOS
+//
+//  Month view navigation and empty-state tests.
+//
+
+import XCTest
+
+final class MonthViewTests: BaseUITestCase {
+    override var seedFixture: String? { "week_of_moods" }
+
+    /// TC-030: Navigate to Month view and verify content is visible.
+    func testMonthView_ContentLoads() {
+        let tabBar = TabBarScreen(app: app)
+        tabBar.tapMonth()
+
+        XCTAssertTrue(tabBar.monthTab.isSelected, "Month tab should be selected")
+
+        // Wait for month view content to load - look for any visible content
+        // Month cards should have mood color cells or month headers
+        let monthContent = app.scrollViews.firstMatch
+        XCTAssertTrue(
+            monthContent.waitForExistence(timeout: 5),
+            "Month view should have scrollable content"
+        )
+
+        captureScreenshot(name: "month_view_with_data")
+    }
+}
+
+final class MonthViewEmptyTests: BaseUITestCase {
+    override var seedFixture: String? { "empty" }
+
+    /// TC-031: Navigate to Month view with no data - should not crash.
+    func testMonthView_EmptyState_NoCrash() {
+        let tabBar = TabBarScreen(app: app)
+        tabBar.tapMonth()
+
+        XCTAssertTrue(tabBar.monthTab.isSelected, "Month tab should be selected")
+
+        // The view should load without crashing, even with no data.
+        // Give it a moment to render.
+        let monthTabStillSelected = tabBar.monthTab.waitForExistence(timeout: 3)
+        XCTAssertTrue(monthTabStillSelected, "App should not crash on empty month view")
+
+        captureScreenshot(name: "month_view_empty")
+    }
+}