Fix login loop on self-hosted desktop (#5022)

# Description of Changes
Fix #5017 

Changes the handling of jwt tokens to be stored in local storage as well
as OS keyring so the rest of the app knows that you're logged in.

frontend/src/proprietary/auth/UseSession.tsx

@@ -126,6 +126,14 @@ export function AuthProvider({ children }: { children: ReactNode }) {
 
     initializeAuth();
 
+    // Listen for jwt-available event (triggered by desktop auth or other sources)
+    const handleJwtAvailable = () => {
+      console.debug('[Auth] JWT available event received, refreshing session');
+      void initializeAuth();
+    };
+
+    window.addEventListener('jwt-available', handleJwtAvailable);
+
     // Subscribe to auth state changes
     const { data: { subscription } } = springAuth.onAuthStateChange(
       async (event: AuthChangeEvent, newSession: Session | null) => {
@@ -162,6 +170,7 @@ export function AuthProvider({ children }: { children: ReactNode }) {
 
     return () => {
       mounted = false;
+      window.removeEventListener('jwt-available', handleJwtAvailable);
       subscription.unsubscribe();
     };
   }, []);

frontend/src/proprietary/auth/springAuthClient.ts

@@ -161,8 +161,8 @@ class SpringAuthClient {
         return { data: { session: null }, error: null };
       }
 
-      // Clear potentially invalid token on other errors too
-      localStorage.removeItem('stirling_jwt');
+      // Don't clear token for other errors (e.g., backend not ready, network issues)
+      // The token is still valid, just can't verify it right now
       return {
         data: { session: null },
         error: { message: getErrorMessage(error, 'Unknown error') },