Refactor demo session architecture: consolidate metadata into fixture files

This commit refactors the demo session architecture to consolidate all demo
configuration data into the fixture files, removing redundant metadata files.

## Changes Made:

### 1. Data Consolidation
- **Removed**: `shared/demo/metadata/demo_users.json`
- **Removed**: `shared/demo/metadata/tenant_configs.json`
- **Updated**: Merged all user data into `02-auth.json` files
- **Updated**: Merged all tenant config data into `01-tenant.json` files

### 2. Enterprise Parent Tenant Updates
- Updated owner name to "Director" (matching auth fixtures)
- Added description field matching tenant_configs.json
- Added `base_tenant_id` to all child tenant entries
- Now includes all 5 child locations (Madrid, Barcelona, Valencia, Seville, Bilbao)

### 3. Professional Tenant Updates
- Added description field from tenant_configs.json
- Ensured consistency with auth fixtures

### 4. Code Updates
- **services/tenant/app/api/internal_demo.py**:
  - Fixed child tenant staff members to use enterprise parent users
  - Changed from professional staff IDs to enterprise staff IDs (Laura López, José Martínez, Francisco Moreno)

- **services/demo_session/app/core/config.py**:
  - Updated DEMO_ACCOUNTS configuration with all 5 child outlets
  - Updated enterprise tenant name and email to match fixtures
  - Added descriptions for all child locations

- **gateway/app/middleware/demo_middleware.py**:
  - Updated comments to reference fixture files as source of truth
  - Clarified that owner IDs come from 01-tenant.json files

- **frontend/src/stores/useTenantInitializer.ts**:
  - Updated tenant names and descriptions to match fixture files
  - Added comments linking to source fixture files

## Benefits:

1. **Single Source of Truth**: All demo data now lives in fixture files
2. **Consistency**: No more sync issues between metadata and fixtures
3. **Maintainability**: Easier to update demo data (one place per tenant type)
4. **Clarity**: Clear separation between template data (fixtures) and runtime config

## Enterprise Demo Fix:

The enterprise owner is now correctly added as a member of all child tenants, fixing
the issue where the tenant switcher didn't show parent/child tenants and the
establishments page didn't load tenants for the demo enterprise user.

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

gateway/app/middleware/demo_middleware.py

@@ -189,10 +189,11 @@ class DemoMiddleware(BaseHTTPMiddleware):
                     request.state.demo_session_status = current_status  # Track status for monitoring
 
                     # Inject demo user context for auth middleware
-                    # Map demo account type to the actual demo user IDs from seed_demo_users.py
+                    # Map demo account type to the actual demo user IDs from fixture files
+                    # These IDs are the owner IDs from the respective 01-tenant.json files
                     DEMO_USER_IDS = {
-                        "professional": "c1a2b3c4-d5e6-47a8-b9c0-d1e2f3a4b5c6",  # María García López
-                        "enterprise": "d2e3f4a5-b6c7-48d9-e0f1-a2b3c4d5e6f7"      # Carlos Martínez Ruiz
+                        "professional": "c1a2b3c4-d5e6-47a8-b9c0-d1e2f3a4b5c6",  # María García López (professional/01-tenant.json -> owner.id)
+                        "enterprise": "d2e3f4a5-b6c7-48d9-e0f1-a2b3c4d5e6f7"      # Director (enterprise/parent/01-tenant.json -> owner.id)
                     }
                     demo_user_id = DEMO_USER_IDS.get(
                         session_info.get("demo_account_type", "professional"),