Fix home navigation bar visibility and hide scan tab title.

Home uses a custom top bar, so TabNavigationController now syncs system nav bar visibility with the stack top; remove the scan tab text label to show icon only.

Co-authored-by: Cursor <cursoragent@cursor.com>

suixinkan_iosTests/MainScanTabItemTests.swift

@@ -35,7 +35,7 @@ final class MainScanTabItemTests: XCTestCase {
         controller.loadViewIfNeeded()
 
         let scanItem = try XCTUnwrap(controller.viewControllers?[2].tabBarItem)
-        XCTAssertEqual(scanItem.title, "扫码")
+        XCTAssertNil(scanItem.title)
         XCTAssertEqual(scanItem.accessibilityIdentifier, "main.scan")
         XCTAssertEqual(scanItem.accessibilityLabel, "扫码核销")
         XCTAssertNotNil(scanItem.image)