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.

docs/developer/modules/config.md

@@ -0,0 +1,27 @@
+# Module: `config`
+
+**Path:** `verae-zapier-middleware/src/config.js`  
+**Phase:** 2  
+**Debug namespace:** `app`
+
+## Purpose
+
+Central runtime settings for HTTP, Verae upstream, NATS flags, and plan limits.
+
+## Exports
+
+### `loadEnvFile()`
+
+Loads `.env` without overriding existing env vars. Called at module load.
+
+### `config`
+
+See [function-reference.md](function-reference.md#configjs) for field table.
+
+### `PLAN_LIMITS`
+
+Default quotas per plan name (`free` | `starter` | `pro` | `enterprise`).
+
+## Environment variables
+
+Documented in `verae-zapier-middleware/.env.example` and root `README.md`.