chore: add missing icons and update seed script

- Add office-building, lock-open, switch-horizontal, x icons
- Remove owner_user_id from vendor creation in seed script

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

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

scripts/seed_demo.py

@@ -390,14 +390,13 @@ def create_demo_vendors(
 
         company = companies[company_index]
 
-        # Create vendor linked to company
+        # Create vendor linked to company (owner is inherited from company)
         vendor = Vendor(
             company_id=company.id,  # Link to company
             vendor_code=vendor_data["vendor_code"],
             name=vendor_data["name"],
             subdomain=vendor_data["subdomain"],
             description=vendor_data["description"],
-            owner_user_id=company.owner_user_id,  # Use company owner (for backward compatibility)
             is_active=True,
             is_verified=True,
             created_at=datetime.now(UTC),