Stabilize iOS UI test foundation and fix flaky suites

Tests iOS/Screens/DayScreen.swift

@@ -19,13 +19,17 @@ struct DayScreen {
     var horribleButton: XCUIElement { app.buttons["mood_button_horrible"] }
 
     /// The mood header container
-    var moodHeader: XCUIElement { app.otherElements["mood_header"] }
+    var moodHeader: XCUIElement { app.element(UITestID.Day.moodHeader) }
 
     // MARK: - Entry List
 
-    /// Find an entry row by its date string (format: "M/d/yyyy")
+    /// Find an entry row by its raw identifier date payload (yyyyMMdd).
     func entryRow(dateString: String) -> XCUIElement {
-        app.descendants(matching: .any).matching(identifier: "entry_row_\(dateString)").firstMatch
+        app.element("\(UITestID.Day.entryRowPrefix)\(dateString)")
+    }
+
+    var anyEntryRow: XCUIElement {
+        app.firstEntryRow
     }
 
     // MARK: - Actions
@@ -37,7 +41,7 @@ struct DayScreen {
             XCTFail("Mood button '\(mood.rawValue)' not found", file: file, line: line)
             return
         }
-        button.coordinate(withNormalizedOffset: CGVector(dx: 0.5, dy: 0.5)).tap()
+        button.tapWhenReady(timeout: 5, file: file, line: line)
 
         // Wait for the celebration animation to finish and entry to appear.
         // The mood header disappears after logging today's mood.
@@ -70,6 +74,14 @@ struct DayScreen {
         )
     }
 
+    func assertAnyEntryExists(file: StaticString = #file, line: UInt = #line) {
+        XCTAssertTrue(
+            anyEntryRow.waitForExistence(timeout: 5),
+            "At least one entry row should exist",
+            file: file, line: line
+        )
+    }
+
     // MARK: - Private
 
     private func moodButton(for mood: MoodChoice) -> XCUIElement {