feat: validate alignment between internship date and day number before saving journal entries

app/Http/Controllers/CareerController.php

@@ -506,14 +506,29 @@ class CareerController extends Controller
             return response()->json(['success' => false, 'message' => 'Hafta sonu günlerine ve resmi tatillere staj günlüğü girilemez.'], 422);
         }
 
-        // 3. Determine if retroactive
+        // 3. Verify alignment of day_number and date based on internship calendar
+        $dates = self::getInternshipDates($intern->internship_start_date, $intern->internship_total_days);
+        $dateToDayMap = [];
+        foreach ($dates as $d) {
+            $dateToDayMap[$d['date']] = $d['day_number'];
+        }
+
+        $expectedDay = $dateToDayMap[$request->date] ?? null;
+        if ($expectedDay === null || $expectedDay != $request->day_number) {
+            return response()->json([
+                'success' => false,
+                'message' => 'Seçilen tarih ve gün sırası uyuşmuyor. Lütfen sayfayı yenileyip tekrar deneyin.'
+            ], 422);
+        }
+
+        // 4. Determine if retroactive
         $isRetroactive = $dateObj->lt(\Carbon\Carbon::today());
 
         $entry = \App\Models\InternshipJournalEntry::updateOrCreate([
             'career_application_id' => $intern->id,
             'day_number' => $request->day_number,
-            'date' => $request->date,
         ], [
+            'date' => $request->date,
             'content' => $request->content,
             'is_retroactive' => $isRetroactive,
             'supervisor_approved' => false,