chore: remove direct avatar upload endpoint (POST /profile/avatar);

feat: add endpoints for presigned upload URLs (GET /upload/avatar, GET /upload/image);
refactor: replace ProfileDto with NewProfileDto in update profile endpoint;
feat: implement S3 integration for avatar management;
fix: update database queries to handle new avatar upload flow;
chore: add new dependencies for S3 handling (golang.org/x/time);
refactor: rename UploadService to S3Service;
refactor: change return type for func LocalizeS3Url(originalURL string) (*url.URL, error);
feat: add custom validator for upload_id

backend/internal/validation/custom.go

@@ -110,6 +110,20 @@ func GetCustomHandlers() []CustomValidatorHandler {
 
 				panic(fmt.Sprintf("'%s' is not a valid verification code type", codeType))
 		}},
+
+		{
+			FieldName: "upload_id",
+			Function: func(fl validator.FieldLevel) bool {
+				uploadType := fl.Param()
+				uploadID := fl.Field().String()
+
+				pattern := fmt.Sprintf(
+					"^%s-([{(]?([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-5][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})[})]?)$", 
+					uploadType,
+				)
+
+				return regexp.MustCompile(pattern).MatchString(uploadID)
+		}},
 		
 	}