feat(stock): batch movement ledger, production batches and shop write-back API

One remaining quantity per batch, kept in ApiCore and always derived:
initial quantity (jarCount / produced quantity) plus the signed movements
in the new BatchMovement ledger, which is never deleted.

- Production batches for MANUFACTURED articles (candles, propolis
  products, ...); articles get a kind and a shop category.
- Withdrawals (farm shop, own use, breakage, sample) and inventory
  corrections on bottlings and production batches, never more than the
  remaining stock; every write locks the bottling or the article row.
- Shop bookings via POST /shop-sync/movements (new scope
  shop-sync:write): idempotent per externalId, articles allocated oldest
  best-before first, returns mirrored onto the batches of the sale,
  invalid entries rejected one by one.
- GET /shop-sync/stock and remainingCount in the shop feed; webhook
  stock.changed after every change (ids only, receivers fetch numbers).
- Bottlings and production batches with movements cannot be deleted.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Backend/src/webhooks/webhook-events.ts

@@ -7,6 +7,10 @@ export const WEBHOOK_EVENTS = [
   'batch.created',
   'batch.updated',
   'product.stock_changed',
+  // Remaining stock of a bottling or production batch changed (sale,
+  // return, withdrawal, correction, corrected initial quantity). Payload:
+  // { bottlingBatchIds, productIds } - receivers fetch the numbers.
+  'stock.changed',
   'task.created',
   'task.completed',
 ] as const;