Add Tests iOS/Screens/ page objects and fix gitignore

The screens/ gitignore rule was matching Tests iOS/Screens/ on
case-insensitive macOS. Anchored to /screens/ (repo root only) so
the 7 UI test page object files are no longer ignored.

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

Tests iOS/Screens/TabBarScreen.swift

@@ -0,0 +1,62 @@
+//
+//  TabBarScreen.swift
+//  Tests iOS
+//
+//  Screen object for the main tab bar navigation.
+//
+
+import XCTest
+
+struct TabBarScreen {
+    let app: XCUIApplication
+
+    // MARK: - Tab Buttons (using localized labels)
+
+    var dayTab: XCUIElement { app.tabBars.buttons["Day"] }
+    var monthTab: XCUIElement { app.tabBars.buttons["Month"] }
+    var yearTab: XCUIElement { app.tabBars.buttons["Year"] }
+    var insightsTab: XCUIElement { app.tabBars.buttons["Insights"] }
+    var settingsTab: XCUIElement { app.tabBars.buttons["Settings"] }
+
+    // MARK: - Actions
+
+    @discardableResult
+    func tapDay() -> DayScreen {
+        dayTab.tapWhenReady()
+        return DayScreen(app: app)
+    }
+
+    @discardableResult
+    func tapMonth() -> TabBarScreen {
+        monthTab.tapWhenReady()
+        return self
+    }
+
+    @discardableResult
+    func tapYear() -> TabBarScreen {
+        yearTab.tapWhenReady()
+        return self
+    }
+
+    @discardableResult
+    func tapInsights() -> TabBarScreen {
+        insightsTab.tapWhenReady()
+        return self
+    }
+
+    @discardableResult
+    func tapSettings() -> SettingsScreen {
+        settingsTab.tapWhenReady()
+        return SettingsScreen(app: app)
+    }
+
+    // MARK: - Assertions
+
+    func assertDayTabSelected() {
+        XCTAssertTrue(dayTab.isSelected, "Day tab should be selected")
+    }
+
+    func assertTabBarVisible() {
+        XCTAssertTrue(dayTab.waitForExistence(timeout: 5), "Tab bar should be visible")
+    }
+}