#200 Apps: Implement app executor and loader

## Parent Epic: #195 ## Description Create the AppExecutor class that loads and executes apps. ## Location engine/apps/executor.py, engine/apps/loader.py ## AppLoader Class ### Responsibilities - Load app class from different entrypoint types - Cache loaded apps (LRU with TTL) - Validate app structure ### Entrypoint Types 1. python_module - Load from installed Python module - Config: {'module': 'path.to.module', 'class': 'ClassName'} 2. python_code - Load from database-stored code - Config: {'code_hash': 'sha256:...', 'class_name': 'MyApp'} - Security: Restricted execution environment 3. webhook - HTTP webhook for external apps - Config: {'url': '...', 'auth_type': 'bearer', 'auth_secret': '...'} ### Security - Sandbox for python_code (no os, eval, exec, etc.) - Timeout for loading - Memory limits ## AppExecutor Class ### Constructor - pool: ConnectionPool - app_cache: LRUCache(maxsize=100, ttl=300) ### execute() Method 1. Load app definition (cached) 2. Verify tenant has app installed 3. Check app status == 'enabled' 4. Load tenant configuration 5. Load secrets from Vault 6. Create AppMetadata 7. Create AppContext wrapper 8. Execute action 9. Log execution to app_execution_log 10. Return result ### Error Handling - AppNotInstalledError - AppDisabledError - ActionNotFoundError - AppExecutionError - SecretNotFoundError ### Integration Points - Called by tool registry wrapper - Uses absurd_client for checkpoints ## Testing - Test each entrypoint type - Test caching behavior - Test error scenarios - Test execution logging