fix: add missing ebay parts visibility helper module

lib/ebay-parts-visibility.ts

@@ -0,0 +1,43 @@
+import type { EbayCacheState } from "@/lib/ebay-parts-match"
+
+type PartLike = {
+  ebayListings?: Array<unknown>
+}
+
+const HIDDEN_CACHE_STATUSES = new Set([
+  "rate_limited",
+  "missing_config",
+  "disabled",
+  "error",
+])
+
+export function hasTrustedPartsListings(parts: PartLike[]) {
+  return parts.some((part) => (part.ebayListings || []).length > 0)
+}
+
+export function shouldShowEbayPartsPanel(args: {
+  isLoading: boolean
+  parts: PartLike[]
+  cache: EbayCacheState | null
+  error: string | null
+}) {
+  if (args.isLoading) {
+    return true
+  }
+
+  const hasListings = hasTrustedPartsListings(args.parts)
+  if (hasListings) {
+    return true
+  }
+
+  const status = args.cache?.status || "idle"
+  if (HIDDEN_CACHE_STATUSES.has(status)) {
+    return false
+  }
+
+  if (args.error) {
+    return false
+  }
+
+  return false
+}