[auth-payment-login-lockout] Make auth intro a clean screen with a back button

App Review rejected the 2026-08 build: tapping checkout as a guest
switched root to .auth, which replaced the whole UI with LoginView as the
NavigationStack root - no nav bar, no back, no dismiss. User was trapped.

- LoginView: rebuilt as a static screen in LCENavigationView with a back
  button that sets root = .main, a 'Criar conta' and an 'Entrar' button,
  and 'Termos de Uso' / 'Politica de Privacidade' links. Added #Preview.
- Forced .preferredColorScheme(.light) and fixed DS colors (the app has
  no dark theme, so system dark mode was inverting the nav bar / title).
- Removed the entry-reveal animation machinery (heroVisible/textVisible/
  buttonVisible/token/prepare flags across LoginView, AuthFlowView,
  ContentView) - dead since guest browsing shipped and the root cause of
  the 2026-08-06 'content stuck hidden' bug.
- enterAuthFlow() is now just root = .auth.
- UITestSupport.ensureLoggedIn taps 'Entrar' (new label).
- ProfileLoggedOutFlowTests: new test covering the choices and the way
  back out of .auth.
- Localizable.xcstrings: catalog caught up to the new/removed strings.

PediFoodsUITests/ProfileLoggedOutFlowTests.swift

@@ -1,10 +1,7 @@
 import XCTest
 
-/// Covers the Profile tab's logged-out state (`ProfileLoggedOutView`) -
-/// confirmed reachable. Actually logging in is blocked by a separate
-/// navigation issue in LoginView's entry-reveal animation, documented in
-/// decisions/2026-08-06-ui-test-account-and-app-attest-bypass.md - not
-/// covered here.
+/// Covers the Profile tab's logged-out state (`ProfileLoggedOutView`) and
+/// the auth intro screen (`LoginView`) it opens.
 final class ProfileLoggedOutFlowTests: XCTestCase {
     override func setUpWithError() throws {
         continueAfterFailure = false
@@ -20,18 +17,27 @@ final class ProfileLoggedOutFlowTests: XCTestCase {
         XCTAssertTrue(app.buttons["Entrar ou Cadastrar"].isHittable)
     }
 
-    func testTappingLoginButtonDoesNotCrash() throws {
+    /// The auth intro screen must offer both entry points plus the legal
+    /// links, and — the reason App Review rejected the build in 2026-08 —
+    /// a working way back out (its `LCENavigationView` back button, which
+    /// sets `root = .main`).
+    func testAuthIntroScreenShowsChoicesAndCanGoBack() throws {
         let app = XCUIApplication()
         app.launch()
         XCTAssertTrue(app.reachLoggedOutProfile())
 
         app.buttons["Entrar ou Cadastrar"].tap()
-        sleep(2)
 
-        // Known limitation (see decisions doc): the login screen's entry
-        // animation doesn't reliably reveal when navigating here from an
-        // already-running guest session, so this only asserts the app is
-        // still alive and responsive, not that login itself completes.
-        XCTAssertEqual(app.state, .runningForeground)
+        XCTAssertTrue(app.buttons["Criar conta"].waitForExistence(timeout: 5), "Auth intro missing 'Criar conta'")
+        XCTAssertTrue(app.buttons["Entrar"].exists, "Auth intro missing 'Entrar'")
+        XCTAssertTrue(app.buttons["Termos de Uso"].exists, "Auth intro missing 'Termos de Uso' link")
+        XCTAssertTrue(app.buttons["Política de Privacidade"].exists, "Auth intro missing 'Política de Privacidade' link")
+
+        let backButton = app.buttons.matching(NSPredicate(format: "label == %@", "Back")).firstMatch
+        XCTAssertTrue(backButton.exists, "Auth intro has no back button — user is trapped")
+        backButton.tap()
+
+        // Back out of `.auth` lands on the main tab bar again.
+        XCTAssertTrue(app.buttons["Home"].waitForExistence(timeout: 5), "Back button did not return to the main flow")
     }
 }