Complete re-validation remediation: KMP architecture, iOS platform, XCUITest rewrite

Phases 1-6 of fixes.md — closes all 13 issues from codex_issues_2.md re-validation:

KMP Architecture:
- Fix subscription purchase/restore response contract (VerificationResponse aligned)
- Add feature benefits auth token + APILayer init flow
- Remove ResidenceFormScreen direct API bypass (use APILayer)
- Wire paywall purchase/restore to real SubscriptionApi calls

iOS Platform:
- Add iOS Keychain token storage via Swift KeychainHelper
- Implement Google Sign-In via ASWebAuthenticationSession (GoogleSignInManager)
- DocumentViewModelWrapper observes DataManager for auto-updates
- Add missing accessibility identifiers (document, task columns, Google Sign-In)

XCUITest Rewrite:
- Rewrite test infrastructure: zero sleep() calls, accessibility ID lookups
- Create AuthCriticalPathTests and NavigationCriticalPathTests
- Delete 14 legacy brittle test files (Suite0-10, templates)
- Fix CaseraTests module import (@testable import Casera)

All platforms build clean. TEST BUILD SUCCEEDED.

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

iosApp/CaseraUITests/PageObjects/MainTabScreen.swift

@@ -2,30 +2,32 @@ import XCTest
 
 /// Page object for the main tab view that appears after login.
 ///
-/// Provides navigation to each tab (Residences, Tasks, Contractors, Documents, Profile)
-/// and a logout flow. Uses predicate-based element lookup to match the existing test patterns.
+/// The app has 4 tabs: Residences, Tasks, Contractors, Documents.
+/// Profile is accessed via the settings button on the Residences screen.
+/// Uses accessibility identifiers for reliable element lookup.
 class MainTabScreen: BaseScreen {
 
     // MARK: - Tab Elements
 
     var residencesTab: XCUIElement {
-        app.tabBars.buttons.containing(NSPredicate(format: "label CONTAINS[c] 'Residences'")).firstMatch
+        app.tabBars.buttons[AccessibilityIdentifiers.Navigation.residencesTab]
     }
 
     var tasksTab: XCUIElement {
-        app.tabBars.buttons.containing(NSPredicate(format: "label CONTAINS[c] 'Tasks'")).firstMatch
+        app.tabBars.buttons[AccessibilityIdentifiers.Navigation.tasksTab]
     }
 
     var contractorsTab: XCUIElement {
-        app.tabBars.buttons.containing(NSPredicate(format: "label CONTAINS[c] 'Contractors'")).firstMatch
+        app.tabBars.buttons[AccessibilityIdentifiers.Navigation.contractorsTab]
     }
 
     var documentsTab: XCUIElement {
-        app.tabBars.buttons.containing(NSPredicate(format: "label CONTAINS[c] 'Documents'")).firstMatch
+        app.tabBars.buttons[AccessibilityIdentifiers.Navigation.documentsTab]
     }
 
-    var profileTab: XCUIElement {
-        app.tabBars.buttons.containing(NSPredicate(format: "label CONTAINS[c] 'Profile'")).firstMatch
+    /// Settings button on the Residences tab (leads to profile/settings).
+    var settingsButton: XCUIElement {
+        app.buttons[AccessibilityIdentifiers.Navigation.settingsButton]
     }
 
     override var isDisplayed: Bool {
@@ -58,18 +60,20 @@ class MainTabScreen: BaseScreen {
         return self
     }
 
+    /// Navigates to settings/profile via the settings button on Residences tab.
     @discardableResult
-    func goToProfile() -> Self {
-        waitForElement(profileTab).tap()
+    func goToSettings() -> Self {
+        goToResidences()
+        waitForElement(settingsButton).tap()
         return self
     }
 
     // MARK: - Logout
 
-    /// Logs out by navigating to the Profile tab and tapping the logout button.
+    /// Logs out by navigating to settings and tapping the logout button.
     /// Handles the confirmation alert automatically.
     func logout() {
-        goToProfile()
+        goToSettings()
 
         let logoutButton = app.buttons[AccessibilityIdentifiers.Profile.logoutButton]
         if logoutButton.waitForExistence(timeout: 5) {