fix: Add getListing method to API client

frontend/src/app/buy/[slug]/page.tsx

@@ -73,7 +73,7 @@ export default function BuyDomainPage() {
     setLoading(true)
     setError(null)
     try {
-      const data = await api.request<Listing>(`/listings/${slug}`)
+      const data = await api.getListing(slug)
       setListing(data)
     } catch (err: any) {
       setError(err.message || 'Listing not found')

frontend/src/lib/api.ts

@@ -432,6 +432,36 @@ class ApiClient {
     }>(`/tld-prices/overview?${params.toString()}`)
   }
 
+  // Listings (Marketplace)
+  async getListings(params?: {
+    search?: string
+    tld?: string
+    min_price?: number
+    max_price?: number
+    sort_by?: string
+    limit?: number
+    offset?: number
+  }) {
+    const query = new URLSearchParams()
+    if (params) {
+      Object.entries(params).forEach(([key, value]) => {
+        if (value !== undefined && value !== null) {
+          query.append(key, String(value))
+        }
+      })
+    }
+    return this.request<{
+      listings: any[]
+      total: number
+      limit: number
+      offset: number
+    }>(`/listings?${query.toString()}`)
+  }
+
+  async getListing(slug: string) {
+    return this.request<any>(`/listings/${slug}`)
+  }
+
   async getTldHistory(tld: string, days = 90) {
     return this.request<{
       tld: string