Fix JSON circular reference serialization and use PayloadCMS generated types

- Replace duplicate type definitions with PayloadCMS generated types
- Fix workflow context serialization with safeSerialize() method
- Resolve type mismatches (id: string vs number)
- Update all imports to use PayloadWorkflow type
- Ensure workflow runs are created successfully without serialization errors

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

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

src/index.ts

@@ -6,12 +6,15 @@ export type {
   CustomTriggerOptions,
   TriggerResult,
   ExecutionContext,
-  Workflow,
-  WorkflowStep,
-  WorkflowTrigger,
   WorkflowsPluginConfig
 } from './types/index.js'
 
+export type {
+  PayloadWorkflow as Workflow,
+  WorkflowStep,
+  WorkflowTrigger
+} from './core/workflow-executor.js'
+
 // Server-side functions are NOT re-exported here to avoid bundling issues
 // Import server-side functions from the /server export instead