feat(centralui): LoginCard sign-in

Replace hand-rolled Bootstrap card with the shared <LoginCard> from ZB.MOM.WW.Theme.
Update ComponentRenderingTests assertions to match LoginCard's rendered structure
(h1.login-title, div.panel.notice.login-error, "Sign in" button text).

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Login.razor

@@ -3,34 +3,8 @@
 @using Microsoft.AspNetCore.Authorization
 @attribute [AllowAnonymous]
 
-<div class="d-flex align-items-center justify-content-center min-vh-100">
+<LoginCard Product="ScadaBridge" Action="/auth/login" Error="@ErrorMessage" />
-    <div class="card shadow-sm" style="max-width: 400px; width: 100%;">
-        <div class="card-body p-4">
-            <h4 class="card-title mb-4 text-center">ScadaBridge</h4>
-
-            @if (!string.IsNullOrEmpty(ErrorMessage))
-            {
-                <div class="alert alert-danger py-2" role="alert">@ErrorMessage</div>
-            }
-
-            <form method="post" action="/auth/login" data-enhance="false">
-                <div class="mb-3">
-                    <label for="username" class="form-label">Username</label>
-                    <input type="text" class="form-control" id="username" name="username"
-                           required autocomplete="username" autofocus />
-                </div>
-                <div class="mb-3">
-                    <label for="password" class="form-label">Password</label>
-                    <input type="password" class="form-control" id="password" name="password"
-                           required autocomplete="current-password" />
-                </div>
-                <button type="submit" class="btn btn-primary w-100">Sign In</button>
-            </form>
-        </div>
-    </div>
-</div>
 
 @code {
-    [SupplyParameterFromQuery(Name = "error")]
+    [SupplyParameterFromQuery(Name = "error")] public string? ErrorMessage { get; set; }
-    public string? ErrorMessage { get; set; }
 }

tests/ZB.MOM.WW.ScadaBridge.CentralUI.Tests/ComponentRenderingTests.cs

@@ -34,7 +34,7 @@ public class ComponentRenderingTests : BunitContext
 
         // Verify submit button
         var submitButton = cut.Find("button[type='submit']");
-        Assert.Contains("Sign In", submitButton.TextContent);
+        Assert.Contains("Sign in", submitButton.TextContent);
     }
 
     [Fact]
@@ -42,7 +42,7 @@ public class ComponentRenderingTests : BunitContext
     {
         var cut = Render<Login>();
 
-        Assert.Throws<Bunit.ElementNotFoundException>(() => cut.Find("div.alert.alert-danger"));
+        Assert.Throws<Bunit.ElementNotFoundException>(() => cut.Find("div.panel.notice.login-error"));
     }
 
     [Fact]
@@ -69,7 +69,7 @@ public class ComponentRenderingTests : BunitContext
     {
         var cut = Render<Login>();
 
-        var title = cut.Find("h4.card-title");
+        var title = cut.Find("h1.login-title");
-        Assert.Equal("ScadaBridge", title.TextContent);
+        Assert.Contains("ScadaBridge", title.TextContent);
     }
 }