refactor(workflow): restructure runner into modular components

Split monolithic runner.ts into separate files for core functionality, execution, waiting state handling, mode management and listeners. Extract types and interfaces into dedicated files for better organization and maintainability. Keep all existing functionality while improving code structure.

Author: moazbuilds

src/workflows/execution/index.ts

@@ -1,4 +1,4 @@
 export * from './run.js';
-export * from './runner.js';
+export * from './runner/index.js';
 export * from './step.js';
 export * from '../behaviors/index.js';

src/workflows/execution/run.ts

@@ -22,7 +22,7 @@ import { registry } from '../../infra/engines/index.js';
 import { MonitoringCleanup } from '../../agents/monitoring/index.js';
 import { WorkflowEventBus, WorkflowEventEmitter } from '../events/index.js';
 import { validateSpecification } from '../../runtime/services/index.js';
-import { WorkflowRunner } from './runner.js';
+import { WorkflowRunner } from './runner/index.js';
 
 export { validateSpecification, ValidationError } from '../../runtime/services/index.js';
 export type { WorkflowStep, WorkflowTemplate };