fix: order calendar deadlines and surface undated tenders

src/services/tenderCalendar.js

@@ -65,3 +65,24 @@ export function calendarMonthDays(month) {
       label:new Date(`${month}-${day}T12:00:00Z`).toLocaleDateString('tr-TR',{weekday:'short',timeZone:'Europe/Istanbul'})};
   });
 }
+
+/** Group once and order each date by known deadline; undated records remain visible. */
+export function calendarAgenda(tenders, now=new Date()) {
+  const days=new Map(),undated=[];
+  for(const tender of tenders){
+    const entry={tender,info:deadlineInfo(tender,now)};
+    if(!entry.info.dateKey){undated.push(entry);continue;}
+    if(!days.has(entry.info.dateKey))days.set(entry.info.dateKey,[]);
+    days.get(entry.info.dateKey).push(entry);
+  }
+  const compare=(a,b)=>{
+    const aTime=a.info.deadline?.getTime(),bTime=b.info.deadline?.getTime();
+    if(aTime!==undefined&&bTime===undefined)return -1;
+    if(aTime===undefined&&bTime!==undefined)return 1;
+    if(aTime!==undefined&&aTime!==bTime)return aTime-bTime;
+    return String(a.tender.ikn || a.tender.id || '').localeCompare(String(b.tender.ikn || b.tender.id || ''),'tr');
+  };
+  for(const entries of days.values())entries.sort(compare);
+  undated.sort(compare);
+  return {days,undated};
+}