Fix remaining 9 UI test failures: subscription state, scroll, timing

- Replace removePersistentDomain with key-by-key removal in resetAppState
  (removePersistentDomain is unreliable on app group UserDefaults suites)
- Add explicit cache clearing in IAPManager.resetForTesting() to prevent
  stale cachedSubscriptionExpiration from restoring .subscribed state
- Use descendants(matching: .any) for upgrade_banner and subscribe_button
  queries (VStack may not match otherElements in SwiftUI)
- Add multiple swipe attempts for icon pack horizontal scroll
- Use coordinate-based drag for onboarding paged TabView advancement
- Add longer wait for Day view refresh after theme change
- Add multiple scroll attempts to find clear data button in Settings

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

Tests iOS/OnboardingTests.swift

@@ -132,9 +132,13 @@ final class OnboardingTests: BaseUITestCase {
     }
 
     /// Swipe left with a brief wait for the page transition to settle.
+    /// Uses a coordinate-based swipe for more reliable page advancement in paged TabView.
     private func swipeAndWait() {
-        app.swipeLeft()
+        // Use a wide swipe from right to left for reliable page advancement
+        let start = app.coordinate(withNormalizedOffset: CGVector(dx: 0.85, dy: 0.5))
+        let end = app.coordinate(withNormalizedOffset: CGVector(dx: 0.15, dy: 0.5))
+        start.press(forDuration: 0.05, thenDragTo: end)
         // Allow the paged TabView animation to settle
-        _ = app.waitForExistence(timeout: 0.5)
+        _ = app.waitForExistence(timeout: 1.0)
     }
 }