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/PaywallGateTests.swift

@@ -0,0 +1,88 @@
+//
+//  PaywallGateTests.swift
+//  Tests iOS
+//
+//  Paywall gate tests: verify paywall overlays appear on premium views
+//  when trial is expired and subscription is not bypassed.
+//  TC-032, TC-039, TC-048
+//
+
+import XCTest
+
+final class PaywallGateTests: BaseUITestCase {
+    override var seedFixture: String? { "empty" }
+    override var bypassSubscription: Bool { false }
+    override var expireTrial: Bool { true }
+
+    /// TC-032: Paywall overlay appears on Month view when trial expired.
+    func testMonthView_PaywallOverlay_WhenTrialExpired() {
+        let tabBar = TabBarScreen(app: app)
+        tabBar.tapMonth()
+
+        // Verify the paywall overlay is present
+        let overlay = app.descendants(matching: .any)
+            .matching(identifier: "paywall_month_overlay")
+            .firstMatch
+        XCTAssertTrue(
+            overlay.waitForExistence(timeout: 5),
+            "Month paywall overlay should appear when trial is expired"
+        )
+
+        // Verify the paywall CTA text is visible
+        let ctaText = app.staticTexts["Explore Your Mood History"]
+        XCTAssertTrue(
+            ctaText.waitForExistence(timeout: 3),
+            "Month paywall CTA text should be visible"
+        )
+
+        captureScreenshot(name: "month_paywall_overlay")
+    }
+
+    /// TC-039: Paywall overlay appears on Year view when trial expired.
+    func testYearView_PaywallOverlay_WhenTrialExpired() {
+        let tabBar = TabBarScreen(app: app)
+        tabBar.tapYear()
+
+        // Verify the paywall overlay is present
+        let overlay = app.descendants(matching: .any)
+            .matching(identifier: "paywall_year_overlay")
+            .firstMatch
+        XCTAssertTrue(
+            overlay.waitForExistence(timeout: 5),
+            "Year paywall overlay should appear when trial is expired"
+        )
+
+        // Verify the paywall CTA text is visible
+        let ctaText = app.staticTexts["See Your Year at a Glance"]
+        XCTAssertTrue(
+            ctaText.waitForExistence(timeout: 3),
+            "Year paywall CTA text should be visible"
+        )
+
+        captureScreenshot(name: "year_paywall_overlay")
+    }
+
+    /// TC-048: Paywall overlay appears on Insights view when trial expired.
+    func testInsightsView_PaywallOverlay_WhenTrialExpired() {
+        let tabBar = TabBarScreen(app: app)
+        tabBar.tapInsights()
+
+        // Verify the paywall overlay is present
+        let overlay = app.descendants(matching: .any)
+            .matching(identifier: "paywall_insights_overlay")
+            .firstMatch
+        XCTAssertTrue(
+            overlay.waitForExistence(timeout: 5),
+            "Insights paywall overlay should appear when trial is expired"
+        )
+
+        // Verify the paywall CTA text is visible
+        let ctaText = app.staticTexts["Unlock AI-Powered Insights"]
+        XCTAssertTrue(
+            ctaText.waitForExistence(timeout: 3),
+            "Insights paywall CTA text should be visible"
+        )
+
+        captureScreenshot(name: "insights_paywall_overlay")
+    }
+}