Remove unused plugin modules and their associated tests

- Delete `init-global-hooks.ts`, `init-step-tasks.ts`, `init-webhook.ts`, and `init-workflow-hooks.ts`
- Remove obsolete components: `TriggerWorkflowButton` and `WorkflowExecutionStatus`
- Clean up unused trigger files: `webhook-trigger.ts`
- Delete webhook-related integration tests: `webhook-triggers.spec.ts`
- Streamline related documentation and improve maintainability by eliminating deprecated code

src/exports/client.ts

@@ -1,7 +1,6 @@
 // Client-side components that may have CSS imports or PayloadCMS UI dependencies
 // These are separated to avoid CSS import errors during Node.js type generation
 
-export { TriggerWorkflowButton } from '../components/TriggerWorkflowButton.js'
 export { StatusCell } from '../components/StatusCell.js'
 export { ErrorDisplay } from '../components/ErrorDisplay.js'