test(e2e): cap live browser contexts to bound Blazor circuit pressure (fixes full-suite timeouts); import negative-test review fixes

tests/ZB.MOM.WW.ScadaBridge.CentralUI.PlaywrightTests/Transport/TransportImportTests.cs

@@ -190,7 +190,7 @@ public class TransportImportTests
             await CliRunner.AddAttributeAsync(tmplId, "Value", "Double");
             await CliRunner.BundleExportAsync(bundlePath, tmplId, "correct-passphrase-1", "src-env");
 
-            var page = await _fixture.NewAuthenticatedPageAsync("multi-role", "password");
+            var page = await _fixture.NewAuthenticatedPageAsync();
 
             // ── STEP 1: Upload ────────────────────────────────────────────────────────
             await page.GotoAsync($"{PlaywrightFixture.BaseUrl}/design/transport/import");
@@ -213,7 +213,9 @@ public class TransportImportTests
             await Assertions.Expect(page.Locator("[data-testid='error-message']"))
                 .ToContainTextAsync("Wrong passphrase. Please try again.", new() { Timeout = 10_000 });
             await Assertions.Expect(page.Locator("#import-passphrase")).ToBeVisibleAsync();
-            await Assertions.Expect(page.Locator("[data-testid='diff-summary']")).ToBeHiddenAsync();
+            // Assert the diff step is genuinely absent (the @switch never rendered it), not merely
+            // hidden — ToBeHiddenAsync is vacuously true for an element that doesn't exist.
+            await Assertions.Expect(page.Locator("[data-testid='diff-summary']")).ToHaveCountAsync(0);
 
             // Secondary indicator: one failed attempt recorded (1 of MaxUnlockAttempts).
             await Assertions.Expect(page.Locator("[data-testid='unlock-attempts']"))