Make backend robust with comprehensive onboarding steps

Backend Changes (services/auth/app/api/onboarding_progress.py):
- Expanded ONBOARDING_STEPS to include all 19 frontend steps
  - Phase 0: user_registered (system)
  - Phase 1: bakery-type-selection, data-source-choice (discovery)
  - Phase 2: setup, smart-inventory-setup, product-categorization, initial-stock-entry (core setup & AI path)
  - Phase 2b: suppliers-setup, inventory-setup, recipes-setup, production-processes (manual path)
  - Phase 3: quality-setup, team-setup (advanced config)
  - Phase 4: ml-training, setup-review, completion (finalization)

- Updated STEP_DEPENDENCIES with granular requirements
  - AI path: smart-inventory-setup → product-categorization → initial-stock-entry
  - Manual path: Independent setup for suppliers, inventory, recipes, processes
  - Flexible ML training: accepts either AI or manual inventory path

- Enhanced ML training validation
  - Supports both AI-assisted path (sales data) and manual inventory path
  - More flexible validation logic for multi-path onboarding

Frontend Changes (UnifiedOnboardingWizard.tsx):
- Fixed auto-complete step name: 'suppliers' → 'suppliers-setup'
- All step IDs now match backend ONBOARDING_STEPS exactly
- Removed temporary step mapping workarounds

Frontend Changes (apiClient.ts):
- Fixed tenant ID requirement warnings for onboarding endpoints
- Added noTenantEndpoints list for user-level endpoints:
  - /auth/me/onboarding (tenant created during onboarding)
  - /auth/me (user profile)
  - /auth/register, /auth/login
- Eliminated false warnings during onboarding flow

This makes the onboarding system fully functional with:
✅ Backend validates all 19 onboarding steps
✅ Proper dependency tracking for multi-path onboarding
✅ No more "Invalid step name" errors
✅ No more tenant ID warnings for onboarding
✅ Robust state tracking for complete user journey

frontend/src/components/domain/onboarding/UnifiedOnboardingWizard.tsx

@@ -57,6 +57,7 @@ const OnboardingWizardContent: React.FC = () => {
   const wizardContext = useWizardContext();
 
   // All possible steps with conditional visibility
+  // All step IDs match backend ONBOARDING_STEPS exactly
   const ALL_STEPS: StepConfig[] = [
     // Phase 1: Discovery
     {
@@ -368,19 +369,19 @@ const OnboardingWizardContent: React.FC = () => {
       // Special handling for smart-inventory-setup
       if (currentStep.id === 'smart-inventory-setup' && data?.shouldAutoCompleteSuppliers) {
         try {
-          console.log('🔄 Auto-completing suppliers step...');
+          console.log('🔄 Auto-completing suppliers-setup step...');
           await markStepCompleted.mutateAsync({
             userId: user.id,
-            stepName: 'suppliers',
+            stepName: 'suppliers-setup',
             data: {
               auto_completed: true,
               completed_at: new Date().toISOString(),
               source: 'inventory_creation_auto_completion',
             }
           });
-          console.log('✅ Suppliers step auto-completed successfully');
+          console.log('✅ Suppliers-setup step auto-completed successfully');
         } catch (supplierError) {
-          console.warn('⚠️ Could not auto-complete suppliers step:', supplierError);
+          console.warn('⚠️ Could not auto-complete suppliers-setup step:', supplierError);
         }
       }