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/CONTRIBUTING.md

@@ -0,0 +1,73 @@
+# Contributing
+
+## Terms
+
+This contributor guide is mainly for Zapier employees. However, zapier-platform is a public repo. Everyone is welcome to submit a pull request (PR). For non-employees, you must agree to the terms of service listed at https://zapier.com/developer-platform/tos (the link is also included in the [LICENSE](license) file) before submitting a PR.
+
+## Local Setup
+
+Install [pnpm][pnpm] if you haven't. We recommend using [asdf](asdf) to install and manage your 
+Node.js and pnpm versions.
+
+Clone this repo with git:
+
+```bash
+git clone git@github.com:zapier/zapier-platform.git
+cd zapier-platform
+```
+
+In the repo directory, install dependencies with pnpm:
+
+```bash
+pnpm install
+```
+
+That's it! Now you have a local environment for development.
+
+## Running Tests
+
+For detailed testing commands and workflow, see [docs-dev/commands.md](docs-dev/commands.md).
+
+Quick overview:
+- `pnpm test` - Run all tests for all packages
+- `pnpm validate` - Full validation (test + smoke-test + lint)
+- Individual packages: `cd` into package directory first, then `pnpm test`
+
+## Testing Guidelines
+
+### Writing Quality Tests
+
+When writing tests, especially for generators and complex components, follow these guidelines to ensure tests are robust and maintainable:
+
+#### ✅ DO: Test Actual Component Behavior
+
+Always test the actual behavior of the component being tested.
+
+#### ❌ DON'T: Use Simulation-Based Testing
+
+Never extract logic from the component and test it in isolation. This creates brittle tests that don't reflect actual behavior.
+
+#### Why Simulation Testing is Problematic
+
+1. **Duplication**: Simulated logic can diverge from actual implementation
+2. **False confidence**: Tests may pass while actual functionality is broken  
+3. **Maintenance burden**: Changes require updating both implementation and simulation
+4. **Missing integration issues**: Doesn't test how components interact with their environment
+
+## Development CLI Setup
+
+For setting up the development version of the CLI, see [docs-dev/install-dev.md](docs-dev/install-dev.md).
+
+## Package Linking for Integration Development
+
+For linking development versions of core and schema packages to your integration projects, see the "Package Linking" section in [docs-dev/commands.md](docs-dev/commands.md).
+
+## Releasing a New Version
+
+**Zapier employees only.** Refer to this [internal doc][releasing] on how to cut a release.
+
+
+[license]: https://github.com/zapier/zapier-platform/blob/main/LICENSE
+[pnpm]: https://pnpm.io/installation
+[asdf]: https://asdf-vm.com
+[releasing]: https://coda.io/d/_di0MgBhlCWf/Releasing-a-New-zapier-platform-Version_su5eD