feat(frontend): enhance 401 handling to clear tokens and redirect

- Update fetch interceptor to special-case 401 responses
- Clear invalid tokens from localStorage on 401 (token, refreshToken, user)
- Distinguish between page navigation and API calls:
  - Page navigation: throw error to prevent further processing
  - API calls: show toast error with session expired message
- Suppress network error toast for redirect errors
- Compile TypeScript to JavaScript

This ensures frontend properly handles expired sessions by clearing
stale credentials and showing appropriate error messages.

web/src/toast.ts

@@ -161,6 +161,31 @@ const setupFetchInterceptor = (): void => {
         try {
             const response = await originalFetch(...args);
 
+            // Special handling for 401 Unauthorized
+            if (response.status === 401) {
+                // Clear invalid tokens from localStorage
+                localStorage.removeItem('token');
+                localStorage.removeItem('refreshToken');
+                localStorage.removeItem('user');
+
+                // Check if this was a page navigation (not API call)
+                const url = args[0] as string;
+
+                // Don't show toast for page navigations - will be handled by redirect
+                if (!url.startsWith('/api/')) {
+                    // Direct navigation to protected page will be caught by middleware
+                    // Just throw to prevent further processing
+                    throw new Error('Session expired');
+                }
+
+                // API call - show toast error
+                const errorMessage = await parseFetchError(response);
+                showToast(errorMessage, 'error');
+
+                return response;
+            }
+
+            // Handle other errors
             if (!response.ok) {
                 const errorMessage = await parseFetchError(response);
                 showToast(errorMessage, 'error');
@@ -168,7 +193,10 @@ const setupFetchInterceptor = (): void => {
 
             return response;
         } catch (error) {
+            // Don't show toast for redirect errors
+            if ((error as Error).message !== 'Session expired') {
                 showToast('Network error: Unable to connect to server', 'error');
+            }
             throw error;
         }
     };