feat(apps): read products by id instead of loading the whole catalogue

Step 3 of docs/CATALOG-PAGINATION-PLAN.md. Step 2 added the targeted
routes; these are the five callers that were fetching all ~16k products
to find a handful of rows:

  product screen    whole catalogue, then find(id)  -> GET /products/:id
  cart re-sync      whole catalogue for 2-3 lines   -> ?ids=
  favourites        whole catalogue, filtered here  -> ?ids=
  home categories   categories derived from it      -> /products/facets
  order row labels  joined on variantId             -> included with the order

Three of these were not merely slow, they were going to be wrong.
Favourites filtered the loaded catalogue, so once the list pages a
favourite outside the loaded slice silently disappears. Home categories
were derived the same way, so a category whose products all sit further
down would vanish from the home screen. Order rows looked their title up
in the catalogue, which ALREADY failed for a product that had since left
the storefront — exactly the old orders history exists for — and
rendered a blank row.

Order labels went to the server rather than to another id lookup: the
item carries productVariantId, not a product id, so ?ids= could not
answer it. One nested include in getOrders returns the variant, its
product and the product's first image. Deliberately NOT filtered by
storefront visibility, so a de-listed product still shows what was
bought; asserted in the new spec. OrderItemCard is synchronous now — no
fetch, no onMounted, the row renders complete on its first frame.

variantLookup is deleted from catalogStore rather than left behind: it
existed only to label order rows, and keeping it would have kept a
reason to load the full catalogue.

getProductsByIds chunks at 100 because the route caps ids there and
drops the rest. A partial answer reads to callers as "these products are
no longer on the storefront" — the cart would silently drop valid lines.
Favourites already run to 874 rows in the imported data (FAV-01).

A failed cart re-sync now leaves the cart alone: it is the person's own
data in localStorage, and dropping lines because the network blinked is
worse than a slightly stale price. The product screen tells a real 404
from a failed request, so only the former renders the not-found page.

One bug introduced and caught while doing this: moving the home
categories to /facets meant memory.init() no longer loaded the catalogue
as a side effect, and the home rails read catalog.products — the home
screen would have rendered empty rails. HomeView now loads it
explicitly. Found by grepping every caller of configStore.init, which is
also how I know HomeView is the only one.

Still on the unpaged list by design: the home rails and the
search/newest lists. Moving those onto paged reads is step 4, kept
separate because it is the risky part — debounce, loading state, and
telling "no results" from "still loading".

api 334/334 across 30 suites; both apps vue-tsc clean. getOrders has a
spec now (3 cases) because its include is a contract both apps depend on
and the method had no test at all. Nothing click-tested — the cart
re-sync and the favourites screen are the two worth a manual pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

apps/user-app/src/stores/cartStore.ts

@@ -1,10 +1,8 @@
 // Ported from legacy henza_pwa/src/store/cartStore.ts, adapted to our string
-// ids and flat (non-paginated) product list. Persisted the same way (a single
-// localStorage key), just via Pinia's own state instead of @vueuse's
-// useStorage wrapping a hand-rolled class.
+// ids. Persisted the same way (a single localStorage key), just via Pinia's own
+// state instead of @vueuse's useStorage wrapping a hand-rolled class.
 import { defineStore } from 'pinia'
-import type { ProductSummary } from '../api/client'
-import { useCatalogStore } from './catalogStore'
+import { api, type ProductSummary } from '../api/client'
 
 export interface CartItem {
   pid: string
@@ -34,16 +32,33 @@ export const useCartStore = defineStore('cart', {
     items: loadFromStorage() as CartItem[],
   }),
   actions: {
-    // Re-syncs cart entries against fresh product data (e.g. price/weight
-    // changes since the item was added), dropping entries whose
-    // product/variant no longer exists — same intent as legacy's init().
+    /**
+     * Re-syncs cart entries against fresh product data (e.g. price/weight
+     * changes since the item was added), dropping entries whose
+     * product/variant no longer exists — same intent as legacy's init().
+     *
+     * Asks for exactly the products in the cart. It used to load the entire
+     * catalogue to look up two or three of them, which with ~16k products meant
+     * downloading all of them every time the app opened.
+     *
+     * A failed request leaves the cart alone: it is the person's own data, held
+     * in localStorage, and dropping items because the network blinked would be
+     * worse than showing a slightly stale price.
+     */
     async init(force = false) {
+      void force // kept for callers; every call now goes to the server anyway
+      if (this.items.length === 0) return
       try {
-        const products = await useCatalogStore().load(force)
+        const ids = [...new Set(this.items.map((i) => i.pid))]
+        const products = await api.getProductsByIds(ids)
+        const byId = new Map(products.map((p) => [p.id, p]))
         const refreshed: CartItem[] = []
         for (const item of this.items) {
-          const product = products.find((p) => p.id === item.pid)
+          const product = byId.get(item.pid)
           const variant = product?.variants.find((v) => v.id === item.vid)
+          // A product the server no longer lists (deactivated, or its photo was
+          // removed) comes back missing, which is the same signal the catalogue
+          // lookup gave before: drop the line.
           if (product && variant) {
             refreshed.push({ ...item, product })
           }