Pull batch, recipe, and inventory data from Brewfather via its REST API

Steps

1. In Brewfather's Settings page, click Generate in the API section to create an API key, selecting the scopes needed (e.g. Read Batches, Edit Batches, Read Recipes, Read/Edit Inventory) — you can only have one API key per account at a time.
2. Authenticate by base64-encoding `userid:apikey` and sending it as `Authorization: Basic <encoded>` on every request.
3. Build against API v2, not v1 — Brewfather's docs flag v1 as deprecated and explicitly recommend migrating to v2; v2 also changed pagination to a `start_after` cursor (replacing v1's `offset`) and raised the rate limit.
4. Call GET https://api.brewfather.app/v2/batches (optionally filtered by `status`, with `include`/`complete` to control payload depth and `limit`/`start_after` for pagination) to list batches, or /v2/batches/:id for a single batch.
5. Call the inventory endpoints (e.g. /v2/inventory/fermentables, /hops, /miscs, /yeasts) to read stock levels, and PATCH the same paths with `inventory` or `inventory_adjust` to set or increment stock from an external system.
6. Respect the rate limit of 500 calls per hour per API key, and handle HTTP 429 responses by honoring the `Retry-After` header.