User-supplied asset ids; brand on product; strain is the name

Four UX changes after using the rework for a bit:

1. Asset ids are 6-digit numbers from a roll of physical labels — server
   no longer generates them. POST /api/inventory requires assetId; the
   add-inventory form has a digits-only input that auto-focuses on entry.
2. Strain and product name are the same thing. Drop products.name; the
   strain's name supplies the display. Product creation just asks for
   "Name (strain)" and matches/creates a strain by that name.
3. Brand moves from inventory_items to products. SKUs are brand-specific,
   so all instances of a product share the brand. Brand selector lives
   on the product create/edit form, not the per-instance form.
4. Scanning an unknown SKU on the add-inventory step now opens the
   create-product subform with the SKU prefilled — one less click.

Migration: detect prior shape (products.name column present) and rename
products/inventory_items/audits to *_v1 archives, recreate empty.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/src/routes/inventory.ts

@@ -1,11 +1,11 @@
 import { Router } from "express";
-import { db, generateAssetId, nextId } from "../db.js";
+import { ASSET_ID_RE, db, nextId } from "../db.js";
 
 export const inventoryRouter: Router = Router();
 
 type CreateBody = {
+  assetId: string;
   productId: string;
-  brandId?: string | null;
   shopId?: string | null;
   binId?: string | null;
   price: number;
@@ -25,6 +25,18 @@ inventoryRouter.post("/inventory", (req, res) => {
   if (!Number.isFinite(body.price) || body.price < 0) {
     return res.status(400).json({ error: "price required" });
   }
+  const assetId = (body.assetId ?? "").trim();
+  if (!ASSET_ID_RE.test(assetId)) {
+    return res.status(400).json({ error: "assetId must be exactly 6 digits" });
+  }
+  const taken = db
+    .prepare<[string], { id: string }>(
+      `SELECT id FROM inventory_items WHERE asset_id = ?`,
+    )
+    .get(assetId);
+  if (taken) {
+    return res.status(409).json({ error: "asset id already in use", id: taken.id });
+  }
 
   const product = db
     .prepare<[string], { id: string; kind: string }>(
@@ -35,19 +47,18 @@ inventoryRouter.post("/inventory", (req, res) => {
 
   const isDiscrete = product.kind === "discrete";
   const id = nextId("inv", "inventory_items");
-  const assetId = generateAssetId();
 
   db.prepare(
     `INSERT INTO inventory_items (
        id, asset_id, product_id,
-       brand_id, shop_id, bin_id,
+       shop_id, bin_id,
        price, thc, cbd, total_cannabinoids,
        weight, last_audit_weight,
        count_original, count_last_audit, unit_weight,
        purchase_date, status
      ) VALUES (
        @id, @assetId, @productId,
-       @brandId, @shopId, @binId,
+       @shopId, @binId,
        @price, @thc, @cbd, @totalCannabinoids,
        @weight, @lastAuditWeight,
        @countOriginal, @countLastAudit, @unitWeight,
@@ -57,7 +68,6 @@ inventoryRouter.post("/inventory", (req, res) => {
     id,
     assetId,
     productId: body.productId,
-    brandId: body.brandId ?? null,
     shopId: body.shopId ?? null,
     binId: body.binId ?? null,
     price: body.price,
@@ -76,7 +86,6 @@ inventoryRouter.post("/inventory", (req, res) => {
 });
 
 type UpdateBody = Partial<{
-  brandId: string | null;
   shopId: string | null;
   binId: string | null;
   price: number;
@@ -95,7 +104,6 @@ inventoryRouter.patch("/inventory/:id", (req, res) => {
 
   type Row = {
     id: string;
-    brand_id: string | null;
     shop_id: string | null;
     bin_id: string | null;
     product_id: string;
@@ -113,7 +121,7 @@ inventoryRouter.patch("/inventory/:id", (req, res) => {
 
   const existing = db
     .prepare<[string], Row>(
-      `SELECT id, brand_id, shop_id, bin_id, product_id, price, thc, cbd,
+      `SELECT id, shop_id, bin_id, product_id, price, thc, cbd,
               total_cannabinoids, weight, last_audit_weight, count_original,
               count_last_audit, unit_weight, purchase_date
          FROM inventory_items WHERE id = ?`,
@@ -132,8 +140,6 @@ inventoryRouter.patch("/inventory/:id", (req, res) => {
     )
     .get(id)!.n;
 
-  const nextBrandId =
-    body.brandId === undefined ? existing.brand_id : body.brandId || null;
   const nextShopId =
     body.shopId === undefined ? existing.shop_id : body.shopId || null;
   const nextBinId =
@@ -174,7 +180,6 @@ inventoryRouter.patch("/inventory/:id", (req, res) => {
 
   db.prepare(
     `UPDATE inventory_items SET
-       brand_id = @brandId,
        shop_id = @shopId,
        bin_id = @binId,
        price = @price,
@@ -190,7 +195,6 @@ inventoryRouter.patch("/inventory/:id", (req, res) => {
      WHERE id = @id`,
   ).run({
     id,
-    brandId: nextBrandId,
     shopId: nextShopId,
     binId: nextBinId,
     price: nextPrice,