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>

Shared/IAPManager.swift

@@ -349,6 +349,16 @@ class IAPManager: ObservableObject {
         return false
     }
 
+    #if DEBUG
+    /// Reset subscription state for UI testing. Called after group defaults are cleared
+    /// so that stale cached state from previous test runs is discarded.
+    func resetForTesting() {
+        state = .unknown
+        lastStatusCheckTime = nil
+        updateTrialState()
+    }
+    #endif
+
     private func updateTrialState() {
         let daysSinceInstall = Calendar.current.dateComponents([.day], from: firstLaunchDate, to: Date()).day ?? 0
         let daysRemaining = trialDays - daysSinceInstall