#646 Tenant Configuration Files

YAML configuration files for platform bootstrap. Files: 1. engine/platform/config/system_tenants.yaml - Defines _platform, platform, demo, test tenants - Owner email, descriptions, is_system flags 2. engine/platform/config/tenant_defaults.yaml - Default rate limits per tool - Schedule definitions (business hours, holidays) - Priority tiers (low, medium, high, critical) 3. engine/platform/config/preinstalled_apps.yaml - List of apps to install on each tenant type - Different apps for system vs customer tenants Config loader in engine/platform/config/loader.py Parent: #639