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>

services/tenant/app/api/internal_demo.py

@@ -719,19 +719,20 @@ async def create_child_outlet(
         )
         db.add(child_owner_member)
 
-        # Create some staff members for the outlet (simplified)
+        # Create staff members for the outlet from parent enterprise users
+        # Use parent's enterprise staff (from enterprise/parent/02-auth.json)
         staff_users = [
             {
-                "user_id": uuid.UUID("50000000-0000-0000-0000-000000000002"),  # Sales user
-                "role": "sales"
+                "user_id": uuid.UUID("f6c54d0f-5899-4952-ad94-7a492c07167a"),  # Laura López - Logistics
+                "role": "logistics_coord"
             },
             {
-                "user_id": uuid.UUID("50000000-0000-0000-0000-000000000003"),  # Quality control user
+                "user_id": uuid.UUID("80765906-0074-4206-8f58-5867df1975fd"),  # José Martínez - Quality
                 "role": "quality_control"
             },
             {
-                "user_id": uuid.UUID("50000000-0000-0000-0000-000000000005"),  # Warehouse user
-                "role": "warehouse"
+                "user_id": uuid.UUID("701cb9d2-6049-4bb9-8d3a-1b3bd3aae45f"),  # Francisco Moreno - Warehouse
+                "role": "warehouse_supervisor"
             }
         ]
 
@@ -743,7 +744,7 @@ async def create_child_outlet(
                 role=staff_member["role"],
                 permissions=json.dumps(["read", "write"]) if staff_member["role"] != "admin" else json.dumps(["read", "write", "admin"]),
                 is_active=True,
-                invited_by=demo_owner_uuid,
+                invited_by=parent_owner_id,
                 invited_at=datetime.now(timezone.utc),
                 joined_at=datetime.now(timezone.utc),
                 created_at=datetime.now(timezone.utc)