Fix ES module bundling issues by isolating pure types

- Create dedicated types-only module (src/types/index.ts) with pure type definitions
- Update main index.ts to export only pure types without runtime imports
- Removes need for serverExternalPackages in Next.js configuration
- Plugin now works "out of the box" without bundling workarounds

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

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

src/index.ts

@@ -1,10 +1,16 @@
 // Main export contains only types and client-safe utilities
 // Server-side functions are exported via '@xtr-dev/payload-automation/server'
 
-// Types only - safe for client bundling
-export type { CustomTriggerOptions, TriggerResult } from './core/trigger-custom-workflow.js'
-export type { ExecutionContext, Workflow, WorkflowStep, WorkflowTrigger } from './core/workflow-executor.js'
-export type { WorkflowsPluginConfig } from './plugin/config-types.js'
+// Pure types only - completely safe for client bundling
+export type {
+  CustomTriggerOptions,
+  TriggerResult,
+  ExecutionContext,
+  Workflow,
+  WorkflowStep,
+  WorkflowTrigger,
+  WorkflowsPluginConfig
+} from './types/index.js'
 
 // Server-side functions are NOT re-exported here to avoid bundling issues
 // Import server-side functions from the /server export instead