fix(server): improve message handling and data privacy

- fix unread count calculation logic in message repository
- implement logic to retrieve other participant's last read sequence in conversation handlers
- mask real names in verification record responses for privacy
- improve error reporting in main entry point by using stderr instead of zap logger during initialization

internal/handler/verification_handler.go

@@ -6,6 +6,7 @@ import (
 	"with_you/internal/dto"
 	"with_you/internal/model"
 	"with_you/internal/pkg/response"
+	"with_you/internal/pkg/sanitizer"
 	"with_you/internal/service"
 
 	"github.com/gin-gonic/gin"
@@ -114,7 +115,7 @@ func convertVerificationRecordToResponse(record *model.VerificationRecord) *dto.
 		UserID:         record.UserID,
 		Identity:       string(record.Identity),
 		Status:         string(record.Status),
-		RealName:       record.RealName,
+		RealName:       sanitizer.MaskValue("real_name", record.RealName),
 		StudentID:      record.StudentID,
 		EmployeeID:     record.EmployeeID,
 		Department:     record.Department,