Milestone 0: import zappier billing, Verae middleware, and Zapier research

Compose-ready workspace: packages/zappier (rate card, portal, Stripe),
packages/verae-zapier-middleware (timestamp + NATS), packages/verae-zapier
(CLI app), vendor/zapier-platform, and research/zapier vendor corpus.

Gate 0 structure checks pass. Product code and research are not yet wired.

vendor/zapier-platform/example-apps/line-items/README.md

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+# line-items
+
+This Zapier integration project is generated by the `zapier-platform init` CLI command.
+
+These are what you normally do next:
+
+```bash
+# Install dependencies
+npm install --ignore-scripts  # or you can use pnpm or yarn
+
+# Run tests
+zapier-platform test
+
+# Register the integration on Zapier if you haven't
+zapier-platform register "App Title"
+
+# Or you can link to an existing integration on Zapier
+zapier-platform link
+
+# Push it to Zapier
+zapier-platform push
+```
+
+Then, to add more features, you can use the `zapier-platform scaffold` command, for example:
+
+```bash
+# Add a trigger
+zapier-platform scaffold trigger contact
+
+# Add an action
+zapier-platform scaffold create contact
+``` 
+
+Find out more on the latest docs: https://docs.zapier.com/platform
+
+# line-items
+
+An example integration demonstrating line item support. Line items are fields
+with a `children` property that represent structured, repeating data — like rows
+in a spreadsheet or items in an order.
+
+## Testing with `zapier-platform invoke`
+
+```bash
+# Non-interactive with JSON input
+zapier-platform invoke create order --non-interactive \
+  -i '{"name": "My Order", "line_items": [{"product_name": "Pens", "quantity": "12", "price": "1.50"}]}'
+
+# Interactive mode — use the line item editing UI
+zapier-platform invoke create order -i '{"name": "My Order"}'
+```