Stabilize iOS UI test foundation and fix flaky suites

Tests iOS/Screens/CustomizeScreen.swift

@@ -13,45 +13,47 @@ struct CustomizeScreen {
     // MARK: - Theme Mode Buttons
 
     func themeButton(named name: String) -> XCUIElement {
-        app.buttons["customize_theme_\(name.lowercased())"]
+        app.buttons[UITestID.Customize.themeButton(name)]
     }
 
     // MARK: - Voting Layout Buttons
 
     func votingLayoutButton(named name: String) -> XCUIElement {
-        app.buttons["customize_voting_\(name.lowercased())"]
+        app.buttons[UITestID.Customize.votingLayoutButton(name)]
     }
 
     // MARK: - Day View Style Buttons
 
     func dayViewStyleButton(named name: String) -> XCUIElement {
-        app.buttons["customize_daystyle_\(name.lowercased())"]
+        app.buttons[UITestID.Customize.dayStyleButton(name)]
+    }
+
+    func iconPackButton(named name: String) -> XCUIElement {
+        app.buttons[UITestID.Customize.iconPackButton(name)]
+    }
+
+    func appThemeCard(named name: String) -> XCUIElement {
+        app.element(UITestID.Customize.appThemeCard(name))
     }
 
     // MARK: - Actions
 
     func selectTheme(_ name: String) {
-        let button = themeButton(named: name)
-        _ = button.waitForExistence(timeout: 5)
-        button.coordinate(withNormalizedOffset: CGVector(dx: 0.5, dy: 0.5)).tap()
+        tapHorizontallyScrollableButton(themeButton(named: name))
     }
 
     func selectVotingLayout(_ name: String) {
-        let button = votingLayoutButton(named: name)
-        if button.exists && !button.isHittable {
-            app.swipeLeft()
-        }
-        _ = button.waitForExistence(timeout: 5)
-        button.coordinate(withNormalizedOffset: CGVector(dx: 0.5, dy: 0.5)).tap()
+        tapHorizontallyScrollableButton(votingLayoutButton(named: name))
     }
 
     func selectDayViewStyle(_ name: String) {
-        let button = dayViewStyleButton(named: name)
-        if button.exists && !button.isHittable {
-            app.swipeLeft()
-        }
-        _ = button.waitForExistence(timeout: 5)
-        button.coordinate(withNormalizedOffset: CGVector(dx: 0.5, dy: 0.5)).tap()
+        tapHorizontallyScrollableButton(dayViewStyleButton(named: name))
+    }
+
+    func selectIconPack(_ name: String) {
+        let button = iconPackButton(named: name)
+        _ = app.swipeUntilExists(button, direction: .up, maxSwipes: 6)
+        button.tapWhenReady(timeout: 5)
     }
 
     // MARK: - Assertions
@@ -63,4 +65,42 @@ struct CustomizeScreen {
             file: file, line: line
         )
     }
+
+    @discardableResult
+    func openThemePicker(file: StaticString = #file, line: UInt = #line) -> Bool {
+        let browseButton = app.element(UITestID.Settings.browseThemesButton)
+        guard browseButton.waitForExistence(timeout: 5) else {
+            XCTFail("Browse Themes button should exist", file: file, line: line)
+            return false
+        }
+        browseButton.tapWhenReady(timeout: 5, file: file, line: line)
+
+        let firstCard = appThemeCard(named: "Zen Garden")
+        return firstCard.waitForExistence(timeout: 5)
+    }
+
+    // MARK: - Private
+
+    private func tapHorizontallyScrollableButton(_ button: XCUIElement) {
+        if button.waitForExistence(timeout: 1) {
+            button.tapWhenReady(timeout: 3)
+            return
+        }
+
+        for _ in 0..<6 {
+            app.swipeLeft()
+            if button.waitForExistence(timeout: 1) {
+                button.tapWhenReady(timeout: 3)
+                return
+            }
+        }
+
+        for _ in 0..<6 {
+            app.swipeRight()
+            if button.waitForExistence(timeout: 1) {
+                button.tapWhenReady(timeout: 3)
+                return
+            }
+        }
+    }
 }