fix: Resolve Quick Start Wizard error display and policy creation issues

- Fixed error response format to send error message as string instead of boolean
- Enhanced error handling in QuickStartWizard to use handleApiError helper
- Improved policy creation with temp directory verification
- Added specific error detection for policy operations
- Fixed error display showing "true" instead of actual error message
- Ensured temp directory exists before writing policy files
- Added file access verification before executing MinIO commands
- Better cleanup of temporary files on failure

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/components/Dashboard/QuickStartWizard.tsx

@@ -41,7 +41,7 @@ import {
 import { useTranslation } from 'react-i18next';
 import userService from '../../services/userService';
 import policyService from '../../services/policyService';
-import api from '../../services/api';
+import api, { handleApiError } from '../../services/api';
 
 interface QuickStartWizardProps {
   open: boolean;
@@ -219,8 +219,9 @@ const QuickStartWizard: React.FC<QuickStartWizardProps> = ({
 
       setCompletedSetup(results);
       setActiveStep(steps.length);
-    } catch (err) {
-      setError(err instanceof Error ? err.message : t('quickWizard:errors.creationFailed'));
+    } catch (err: any) {
+      const errorMessage = handleApiError(err);
+      setError(errorMessage);
       setIsCreating(false);
     } finally {
       setLoading(false);
@@ -297,7 +298,7 @@ const QuickStartWizard: React.FC<QuickStartWizardProps> = ({
               value={setupData.userPassword}
               onChange={(e) => setSetupData({ ...setupData, userPassword: e.target.value })}
               error={!!error && activeStep === 1}
-              helperText={error || t('quickWizard:user.passwordHelper')}
+              helperText={(error && activeStep === 1 ? error : '') || t('quickWizard:user.passwordHelper')}
               InputProps={{
                 endAdornment: (
                   <InputAdornment position="end">