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/CustomizeScreen.swift

@@ -0,0 +1,65 @@
+//
+//  CustomizeScreen.swift
+//  Tests iOS
+//
+//  Screen object for the Customize sub-tab — theme, voting layout, and day view style pickers.
+//
+
+import XCTest
+
+struct CustomizeScreen {
+    let app: XCUIApplication
+
+    // MARK: - Theme Mode Buttons
+
+    func themeButton(named name: String) -> XCUIElement {
+        app.buttons["customize_theme_\(name.lowercased())"]
+    }
+
+    // MARK: - Voting Layout Buttons
+
+    func votingLayoutButton(named name: String) -> XCUIElement {
+        app.buttons["customize_voting_\(name.lowercased())"]
+    }
+
+    // MARK: - Day View Style Buttons
+
+    func dayViewStyleButton(named name: String) -> XCUIElement {
+        app.buttons["customize_daystyle_\(name.lowercased())"]
+    }
+
+    // MARK: - Actions
+
+    func selectTheme(_ name: String) {
+        let button = themeButton(named: name)
+        button.tapWhenReady()
+    }
+
+    func selectVotingLayout(_ name: String) {
+        let button = votingLayoutButton(named: name)
+        // May need to scroll horizontally to find it
+        if !button.isHittable {
+            app.swipeLeft()
+        }
+        button.tapWhenReady()
+    }
+
+    func selectDayViewStyle(_ name: String) {
+        let button = dayViewStyleButton(named: name)
+        // May need to scroll horizontally to find it
+        if !button.isHittable {
+            app.swipeLeft()
+        }
+        button.tapWhenReady()
+    }
+
+    // MARK: - Assertions
+
+    func assertThemeButtonExists(_ name: String, file: StaticString = #file, line: UInt = #line) {
+        XCTAssertTrue(
+            themeButton(named: name).waitForExistence(timeout: 5),
+            "Theme button '\(name)' should exist",
+            file: file, line: line
+        )
+    }
+}