[batch-f] Extend Checkout coverage: payment method selection + Alterar

Adds testCheckoutPaymentMethodSelectionAndAddressAlterar, exercising
CheckoutView's payment-method row selection and the address picker's
"Alterar" entry point without ever tapping "Confirmar e Pagar" -
deliberately not submitting a real order (explicit user direction:
cover the screen, don't create real order data in the QA account).

Extracted the shared reach-checkout steps from
testAddProductToCartAndReachCheckout into a private helper,
reachCheckoutWithOneItem, reused by both tests.

Fixed the same "not hittable" Back-button bug (already documented in
UITestSupport.swift) inline here too - tapping a Back button that
exists but is mid pop-transition throws a fatal, uncatchable failure;
needs an .isHittable check with a short poll, not just .exists.

Verified stable across 2 consecutive class-level runs.

PediFoodsUITests/CartCheckoutFlowTests.swift

@@ -17,6 +17,67 @@ final class CartCheckoutFlowTests: XCTestCase {
     func testAddProductToCartAndReachCheckout() throws {
         let app = XCUIApplication()
         app.launch()
+        try reachCheckoutWithOneItem(app)
+    }
+
+    /// Exercises CheckoutView's payment-method selection and the address
+    /// picker's "Alterar" entry point without ever tapping "Confirmar e
+    /// Pagar" - deliberately not submitting a real order (per explicit
+    /// user direction: cover the screen, don't create real order data).
+    func testCheckoutPaymentMethodSelectionAndAddressAlterar() throws {
+        let app = XCUIApplication()
+        app.launch()
+        try reachCheckoutWithOneItem(app)
+
+        XCTAssertTrue(app.staticTexts["MÉTODO DE PAGAMENTO"].waitForExistence(timeout: 5))
+
+        // PIX is the default selection; only tap an alternative if this
+        // store's real catalog actually offers one - don't assume Cartão
+        // de Crédito exists (in-app payment methods depend on real store
+        // config, already found to vary - see the standing-account state
+        // notes in decisions/2026-08-06-ui-test-account-and-app-attest-bypass.md).
+        let creditCardRow = app.buttons.matching(NSPredicate(format: "label CONTAINS[c] %@", "Cartão de Crédito")).firstMatch
+        if creditCardRow.exists {
+            creditCardRow.tap()
+        }
+
+        XCTAssertTrue(app.staticTexts["TIPO DE ENTREGA"].waitForExistence(timeout: 5))
+
+        app.buttons["Alterar"].tap()
+        XCTAssertTrue(
+            app.staticTexts["Meus Endereços"].waitForExistence(timeout: 10),
+            "Alterar never opened the address picker"
+        )
+
+        // Dismiss without changing anything, back to Checkout. .isHittable,
+        // not just .exists: a Back button that exists but is mid-transition
+        // throws a fatal, uncatchable "not hittable" failure on tap - same
+        // issue already fixed in UITestSupport.reachProfileTabRegardlessOfAuthState.
+        // Poll briefly since the push-in animation can still be settling
+        // right after "Meus Endereços" first becomes visible.
+        let backButton = app.buttons.matching(NSPredicate(format: "label == %@", "Back")).firstMatch
+        var dismissed = false
+        for _ in 0..<10 {
+            if backButton.exists, backButton.isHittable {
+                backButton.tap()
+                dismissed = true
+                break
+            }
+            usleep(200_000)
+        }
+        if dismissed == false {
+            app.swipeDown()
+        }
+        if app.staticTexts["Finalizar Pedido"].waitForExistence(timeout: 10) == false {
+            let dir = "/private/tmp/claude-501/-Users-loverde-co-Documents-Loverde-JOBs-Producao-Loverde-Co-LC-RAG-Struct-projects-PediFoods-ios/4a9ec4f7-c3ad-4cf5-8dad-073446f6fd81/scratchpad"
+            try? app.screenshot().pngRepresentation.write(to: URL(fileURLWithPath: "\(dir)/after_alterar_dismiss.png"))
+        }
+        XCTAssertTrue(app.staticTexts["Finalizar Pedido"].exists, "Never returned to Checkout")
+
+        // Deliberately not tapping "Confirmar e Pagar" - see doc comment.
+    }
+
+    private func reachCheckoutWithOneItem(_ app: XCUIApplication) throws {
         XCTAssertTrue(app.ensureLoggedIn(), "Login never completed")
 
         // ensureLoggedIn can land on whichever tab it detected the