fix(litellm): add error handling in onboarding wizard

The AUTH_CHOICE_CANCELLED error was showing to users during onboarding
because the applyAuthChoice call in onboarding.ts wasn't wrapped in
error handling. This adds the same try-catch loop pattern used in
configure.gateway-auth.ts and agents.commands.add.ts to properly
handle the cancellation and re-prompt for auth method selection.

src/wizard/onboarding.ts

@@ -21,6 +21,7 @@ import { promptRemoteGatewayConfig } from "../commands/onboard-remote.js";
 import { setupSkills } from "../commands/onboard-skills.js";
 import { setupInternalHooks } from "../commands/onboard-hooks.js";
 import type {
+  AuthChoice,
   GatewayAuthChoice,
   OnboardMode,
   OnboardOptions,
@@ -354,7 +355,11 @@ export async function runOnboardingWizard(
     allowKeychainPrompt: false,
   });
   const authChoiceFromPrompt = opts.authChoice === undefined;
-  const authChoice =
+  let authChoice: AuthChoice;
+
+  // Loop to allow retrying auth choice if user cancels during configuration
+  while (true) {
+    authChoice =
       opts.authChoice ??
       (await promptAuthChoiceGrouped({
         prompter,
@@ -362,6 +367,7 @@ export async function runOnboardingWizard(
         includeSkip: true,
       }));
 
+    try {
       const authResult = await applyAuthChoice({
         authChoice,
         config: nextConfig,
@@ -374,6 +380,18 @@ export async function runOnboardingWizard(
         },
       });
       nextConfig = authResult.config;
+      break; // Success - exit the loop
+    } catch (error) {
+      // If user cancelled to go back to auth selection, loop again
+      if (error instanceof Error && error.message === "AUTH_CHOICE_CANCELLED") {
+        // Clear opts.authChoice so we prompt again
+        opts.authChoice = undefined;
+        continue;
+      }
+      // Re-throw other errors
+      throw error;
+    }
+  }
 
   if (authChoiceFromPrompt) {
     const modelSelection = await promptDefaultModel({