Add company-scoped unit list/upsert/delete and article unit patches.

Units are isolated per company; article detail exposes full unit shape, and unused units can be deleted safely via FK NO ACTION.

README.md

@@ -117,6 +117,38 @@ Backend mapping:
 
 ---
 
+## `unit`
+
+| Method | Signature | Returns |
+| --- | --- | --- |
+| `list` | `(googleAuthId, companyId)` | `{ si, basesi, basesifactor, symbol, name }[]` |
+| `upsert` | `(googleAuthId, companyId, { si, basesi, basesifactor, symbol, name })` | `{ si, basesi, basesifactor, symbol, name }` |
+| `delete` | `(googleAuthId, companyId, si)` | `void` |
+
+Shape (überall):
+
+```js
+{ si, basesi, basesifactor, symbol, name }
+```
+
+`symbol` / `name` come from `unittext` in the company default language (`LEFT JOIN`; missing → `null`). Sorted by `symbol`, `name`, `si`. Units are **company-scoped** (`unit.company_id`); Unique is `(company_id, si)`.
+
+### `list`
+
+Auth via `resolveCompanyAccess` (like `getTreeForCompany`). Returns only units of that company. Errors: `Company not found`, `Not authorized`.
+
+### `upsert`
+
+Match key `(companyId, si)`. Inserts `unit` + `unittext`, or updates `basesi` / `basesifactor` and upserts `unittext` for the company language. `basesifactor` must be finite and `> 0`. Errors: `Company not found`, `Not authorized`, `Invalid unit`.
+
+Default article unit `pc` is ensured **per company** on article create (with `unittext` symbol/name `pc` / `Piece` for the company language).
+
+### `delete`
+
+Deletes the unit for `(companyId, si)`. Blocked by FK if any article still references it (`Unit in use`). Missing → `Unit not found`. Errors: `Company not found`, `Not authorized`, `Unit not found`, `Unit in use`.
+
+---
+
 ## `category`
 
 | Method | Signature | Returns |
@@ -143,7 +175,7 @@ Backend mapping:
 | --- | --- | --- |
 | `createUnderParent` | `({ googleAuthId, parentId, name })` | `{ id, parentId, name, sku }` |
 | `getBySku` | `(googleAuthId, sku)` | detail object (see below) |
-| `updateBySku` | `(googleAuthId, sku, { name })` | same shape as `getBySku` |
+| `updateBySku` | `(googleAuthId, sku, { name?, unitamount?, unitSi? })` | same shape as `getBySku` |
 | `setPricesBySku` | `(googleAuthId, sku, [{ price, tax, minmultiplier? }])` | same shape as `getBySku` |
 | `addImage` | `(googleAuthId, sku, imageBuffer)` | image result (see below) |
 | `deleteImage` | `(googleAuthId, sku, fullHash)` | `void` |
@@ -171,7 +203,7 @@ Backend mapping:
 {
   id, sku, name, slug,
   unitamount, weight,
-  unit: { si },
+  unit: { si, basesi, basesifactor, symbol, name },
   brand: { name, thumbW, thumbH, thumbHash } | null,
   categoryIds: number[],
   photos: { sort, fullHash, thumbW, thumbH, thumbHash }[],
@@ -188,7 +220,7 @@ Backend mapping:
 
 Auth via the article's `categoryarticle` category + `resolveCategoryAccess`. Errors: `Article not found`, `Not authorized`.
 
-`updateBySku` updates `articletext` (company default language) in a transaction (`name` + slugified `slug`), then returns the same object as `getBySku`. Errors: `Article not found`, `Not authorized`, `Name required`.
+`updateBySku` patches article fields in a transaction. At least one of `name`, `unitamount`, `unitSi` required. `name` → `articletext` (slugified `slug`); empty name → `Name required`. `unitSi` → existing `unit.si` lookup (no silent ensure); unknown → `Unit not found`. `unitamount` must be finite and `> 0` → `Invalid unitamount`. Returns the same object as `getBySku`. Errors: `Article not found`, `Not authorized`, `Name required`, `Unit not found`, `Invalid unitamount`.
 
 `setPricesBySku` replaces all `price` rows for the article’s company `poscustomergroup_id` in one transaction. Each entry: `price` → `net`, `tax` → tax rate (ensured via `tax.ensure`), `minmultiplier` defaults to `1`. Empty array clears all POS prices. Returns the same object as `getBySku`. Errors: `Article not found`, `Not authorized`, `POS customer group required`, `Invalid prices`.
 
@@ -237,9 +269,12 @@ res.set('Content-Type', thumb.contentType).send(thumb.buffer);
 | `GET /api/category/tree?companyId=` | `category.getTreeForCompany(googleAuthId, companyId)` |
 | `POST /api/category` | `category.createUnderParent({ googleAuthId, parentId, name })` |
 | `DELETE /api/category/:id` | `category.delete({ googleAuthId, id })` |
+| `GET /api/unit?companyId=` | `unit.list(googleAuthId, companyId)` |
+| `PUT /api/unit` | `unit.upsert(googleAuthId, companyId, { si, basesi, basesifactor, symbol, name })` |
+| `DELETE /api/unit` | `unit.delete(googleAuthId, companyId, si)` |
 | `POST /api/article` | `article.createUnderParent({ googleAuthId, parentId, name })` |
 | `GET /api/article/:sku` | `article.getBySku(googleAuthId, sku)` |
-| `PATCH /api/article/:sku` | `article.updateBySku(googleAuthId, sku, { name })` |
+| `PATCH /api/article/:sku` | `article.updateBySku(googleAuthId, sku, { name?, unitamount?, unitSi? })` |
 | `PUT /api/article/:sku/prices` | `article.setPricesBySku(googleAuthId, sku, [{ price, tax, minmultiplier? }])` |
 | `DELETE /api/article/:sku` | `article.delete(googleAuthId, sku)` |
 | `POST /api/article/:sku/image` | `article.addImage(googleAuthId, sku, imageBuffer)` |