Fix remaining 12 UI test failures: subscription state, hittability, tab selection

- IAPManager: add resetForTesting() to discard stale cached subscription state
- UITestMode: call resetForTesting() after clearing defaults (fixes 5 banner tests)
- StabilityTests: use NSPredicate wait for isSelected (iOS 26 Liquid Glass)
- SettingsActionTests: use coordinate tap for clear data and analytics toggle
- IconPackTests: add horizontal scroll fallback for off-screen icon packs

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

Tests iOS/IconPackTests.swift

@@ -36,7 +36,11 @@ final class IconPackTests: BaseUITestCase {
         for pack in allIconPacks {
             let button = app.buttons["customize_iconpack_\(pack)"]
             if !button.exists {
-                // Scroll more to reveal buttons off-screen
+                // Icon packs may be in a horizontal scroll — try swipe left first
+                app.swipeLeft()
+            }
+            if !button.exists {
+                // If still not found, try scrolling the page down
                 app.swipeUp()
             }
             if button.waitForExistence(timeout: 3) {