fix: Align search parameters and correct health check endpoint

frontend/app/page.tsx

@@ -94,7 +94,7 @@ export default function HomePage() {
     window.history.pushState({}, '', `?tab=agent_analysis`);
   };
 
-  const handleSearch = async (params: { keyword?: string; buyer_code?: string; provider_code?: string; date?: string; skip?: number; limit?: number }) => {
+  const handleSearch = async (params: { keyword?: string; buyer?: string; provider_code?: string; date?: string; skip?: number; limit?: number }) => {
     const results = await searchTenders(params);
     setTenders(results);
   };

frontend/components/TenderSearch.tsx

@@ -56,7 +56,7 @@ export default function TenderSearch({ tenders, onSearch, onAnalyze, forceShowFo
     try {
       await onSearch({ 
         keyword, 
-        buyer_code: buyerCode, 
+        buyer: buyerCode, 
         date,
         skip: (page - 1) * itemsPerPage, 
         limit: itemsPerPage 

frontend/lib/api.ts

@@ -7,7 +7,7 @@ const jsonHeaders = {
 };
 
 export async function healthCheck() {
-  const res = await fetch(`${API_BASE}/health`);
+  const res = await fetch(`${API_BASE}/api/health`);
   if (!res.ok) {
     throw new Error("Health check failed");
   }
@@ -22,7 +22,7 @@ export async function fetchDbStatus() {
 
 export async function searchTenders(params: { 
   keyword?: string; 
-  buyer_code?: string; 
+  buyer?: string; 
   provider_code?: string; 
   date?: string;
   skip?: number;
@@ -30,7 +30,7 @@ export async function searchTenders(params: {
 }): Promise<Tender[]> {
   const query = new URLSearchParams();
   if (params.keyword) query.append("keyword", params.keyword);
-  if (params.buyer_code) query.append("buyer_code", params.buyer_code);
+  if (params.buyer) query.append("buyer", params.buyer);
   if (params.provider_code) query.append("provider_code", params.provider_code);
   if (params.date) query.append("date", params.date);
   if (params.skip !== undefined) query.append("skip", params.skip.toString());