fix(market): re-link stallName when stall arrives after product

Subscription delivers stall (kind 30017) and product (kind 30018)
events without ordering guarantees. handleProductEvent and
loadProducts looked up stall name once at product-ingest time and
froze "Unknown Stall" on the product object when the stall hadn't
arrived yet — even when the stall landed milliseconds later.

Two-sided fix in the Pinia store:

- addStall: after upserting a stall, sweep products and re-stamp
  stallName for any matching stall_id (handles product-arrives-first
  race + downstream stall name updates).
- addProduct: do the lookup itself instead of trusting the caller's
  stallName field (handles stall-arrives-first race + paranoia).

Both paths converge on the live stalls collection, so eventual
consistency is guaranteed regardless of event order.

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

src/modules/market/stores/market.ts

@@ -239,11 +239,20 @@ export const useMarketStore = defineStore('market', () => {
   }
   
   const addProduct = (product: Product) => {
-    const existingIndex = products.value.findIndex(p => p.id === product.id)
+    // Lookup stallName from the current stall set — the value passed in by
+    // the caller can be stale ("Unknown Stall") if the stall event hadn't
+    // arrived yet. The reverse race (stall arrives first) is handled in
+    // addStall below.
+    const matchedStall = stalls.value.find(s => s.id === product.stall_id)
+    const enriched: Product = matchedStall
+      ? { ...product, stallName: matchedStall.name }
+      : product
+
+    const existingIndex = products.value.findIndex(p => p.id === enriched.id)
     if (existingIndex >= 0) {
-      products.value[existingIndex] = product
+      products.value[existingIndex] = enriched
     } else {
-      products.value.push(product)
+      products.value.push(enriched)
     }
   }
 
@@ -254,6 +263,14 @@ export const useMarketStore = defineStore('market', () => {
     } else {
       stalls.value.push(stall)
     }
+    // Re-stamp stallName on any products that arrived before this stall did
+    // (or whose stall name has changed). Direct property mutation on items
+    // in a reactive array triggers Vue's deep reactivity.
+    products.value.forEach(p => {
+      if (p.stall_id === stall.id && p.stallName !== stall.name) {
+        p.stallName = stall.name
+      }
+    })
   }
   
   const addMarket = (market: Market) => {