fix: expose tender detail loading errors and retry

tests/tender-detail-fetch.test.mjs

@@ -0,0 +1,22 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import {fetchTenderDetail} from '../src/services/tenderApi.js';
+test('detail loading rejects empty source, supports retry and stops on timeout/cancel',async()=>{
+  const original=globalThis.fetch;
+  try {
+    globalThis.fetch=async()=>new Response(JSON.stringify({success:true,aciklama:''}));
+    await assert.rejects(()=>fetchTenderDetail('ilan-1'),/Kaynak ilan metni alınamadı/);
+    globalThis.fetch=async()=>new Response(JSON.stringify({success:true,aciklama:'Tam ilan metni'}));
+    assert.equal((await fetchTenderDetail('ilan-1')).aciklama,'Tam ilan metni');
+    globalThis.fetch=async()=>new Response('error',{status:503});
+    await assert.rejects(()=>fetchTenderDetail('ilan-1'),/HTTP 503/);
+    globalThis.fetch=async(url,{signal})=>new Promise((resolve,reject)=>{
+      if(signal.aborted) reject(new DOMException('Cancelled','AbortError'));
+      else signal.addEventListener('abort',()=>reject(new DOMException('Cancelled','AbortError')),{once:true});
+    });
+    await assert.rejects(()=>fetchTenderDetail('ilan-1',{timeoutMs:5}),/zaman aşımı/);
+    const controller=new AbortController();
+    const pending=fetchTenderDetail('ilan-1',{signal:controller.signal});controller.abort();
+    await assert.rejects(()=>pending,{name:'AbortError'});
+  } finally { globalThis.fetch=original; }
+});