Self-hosted desktop SSO (#5265)

# Description of Changes
Support SSO in self-hosted desktop app.

---------

Co-authored-by: Anthony Stirling <[email protected]>

frontend/src/proprietary/routes/AuthCallback.module.css

@@ -0,0 +1,129 @@
+.page {
+  min-height: 100vh;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 50px 20px;
+  background: #f5f5f5;
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
+}
+
+.card {
+  background: #ffffff;
+  border-radius: 12px;
+  padding: 40px;
+  max-width: 420px;
+  width: 100%;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+  text-align: center;
+  color: #1a1a1a;
+  border: 1px solid #e5e7eb;
+}
+
+.icon {
+  font-size: 48px;
+  margin-bottom: 16px;
+}
+
+.iconSuccess {
+  color: #2e7d32;
+}
+
+.iconError {
+  color: #d32f2f;
+}
+
+.iconNeutral {
+  color: #4b5563;
+}
+
+.title {
+  font-size: 24px;
+  font-weight: 600;
+  margin-bottom: 12px;
+  color: #1a1a1a;
+}
+
+.message {
+  color: #666;
+  line-height: 1.6;
+  font-size: 15px;
+}
+
+.loadingExtra {
+  color: #6b7280;
+  margin-top: 12px;
+  font-size: 14px;
+}
+
+.errorBox {
+  margin-top: 20px;
+  background: #ffebee;
+  border: 1px solid #ffcdd2;
+  border-radius: 8px;
+  padding: 16px;
+  color: #c62828;
+  font-size: 14px;
+  line-height: 1.5;
+  word-break: break-word;
+  text-align: left;
+}
+
+@media (prefers-color-scheme: dark) {
+  .page {
+    background: #1a1a1a;
+    color: #e0e0e0;
+  }
+
+  .card {
+    background: #2d2d2d;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
+    color: #e5e7eb;
+    border-color: #374151;
+  }
+
+  .iconSuccess {
+    color: #66bb6a;
+  }
+
+  .iconError {
+    color: #ef5350;
+  }
+
+  .iconNeutral {
+    color: #9ca3af;
+  }
+
+  .title {
+    color: #f5f5f5;
+  }
+
+  .message,
+  .loadingExtra {
+    color: #b0b0b0;
+  }
+
+  .errorBox {
+    background: #3d2020;
+    border: 1px solid #5d3030;
+    color: #ef9a9a;
+  }
+}
+
+@media (max-width: 480px) {
+  .page {
+    padding: 20px 16px;
+  }
+
+  .card {
+    padding: 32px 24px;
+  }
+
+  .title {
+    font-size: 20px;
+  }
+
+  .icon {
+    font-size: 40px;
+  }
+}

frontend/src/proprietary/routes/AuthCallback.test.tsx

@@ -172,6 +172,6 @@ describe('AuthCallback', () => {
       </BrowserRouter>
     );
 
-    expect(getByText('Completing authentication...')).toBeInTheDocument();
+    expect(getByText('Completing authentication')).toBeInTheDocument();
   });
 });

frontend/src/proprietary/routes/AuthCallback.tsx

@@ -1,6 +1,8 @@
 import { useEffect } from 'react';
 import { useNavigate } from 'react-router-dom';
 import { springAuth } from '@app/auth/springAuthClient';
+import { handleAuthCallbackSuccess } from '@app/extensions/authCallback';
+import styles from '@app/routes/AuthCallback.module.css';
 
 /**
  * OAuth Callback Handler
@@ -52,6 +54,8 @@ export default function AuthCallback() {
           return;
         }
 
+        await handleAuthCallbackSuccess(token);
+
         console.log('[AuthCallback] Token validated, redirecting to home');
 
         // Clear the hash from URL and redirect to home page
@@ -69,17 +73,12 @@ export default function AuthCallback() {
   }, [navigate]);
 
   return (
-    <div style={{
-      display: 'flex',
-      alignItems: 'center',
-      justifyContent: 'center',
-      height: '100vh'
-    }}>
-      <div className="text-center">
-        <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-blue-600 mx-auto mb-3"></div>
-        <div className="text-gray-600">
-          Completing authentication...
-        </div>
+    <div className={styles.page}>
+      <div className={styles.card}>
+        <div className={`${styles.icon} ${styles.iconNeutral}`}>...</div>
+        <div className={styles.title}>Completing authentication</div>
+        <div className={styles.message}>Please wait while we finish signing you in.</div>
+        <div className={styles.loadingExtra}>You can close this window once it completes.</div>
       </div>
     </div>
   );