docs: clarify intended usage and Docker vs Edge guidance

docs/intended-usage.md

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+## Intended Usage
+
+This engine is designed for working with Stripe data **after** events occur.
+It focuses on data ingestion, synchronization, and analytics.
+
+### This engine IS intended for:
+
+- Syncing Stripe data to databases or warehouses
+- Processing Stripe webhooks
+- Running analytics and reporting
+- Building dashboards on Stripe data
+
+### This engine is NOT intended for:
+
+- Handling Stripe Checkout
+- Processing live payments
+- Creating or managing sales flows
+- Replacing Stripe’s official SDKs
+
+## Should I use this engine?
+
+| Use case              | Should I use this? |
+| --------------------- | ------------------ |
+| Accept payments       | ❌ No              |
+| Stripe Checkout       | ❌ No              |
+| Subscription creation | ❌ No              |
+| Sync Stripe data      | ✅ Yes             |
+| Analytics & reporting | ✅ Yes             |
+| Webhook processing    | ✅ Yes             |
+
+## Docker vs Edge Usage
+
+### Docker
+
+Use Docker when you need:
+
+- Long-running sync jobs
+- Batch processing
+- High data volumes
+- Stable server environments
+
+### Edge
+
+Use Edge when you need:
+
+- Low-latency webhook handling
+- Lightweight event processing
+- Serverless deployments
+
+⚠️ Edge is not recommended for heavy analytics or long-running jobs.
+
+## Example Usage
+
+If you are starting a new project and want to accept Stripe payments:
+
+- Use Stripe Checkout or Stripe SDKs
+- Use this engine only to sync data and run analytics
+
+If you already accept payments and want reporting or dashboards:
+
+- This engine is an appropriate tool