bugfix: appointment hours now use the client timezone on UTC servers.

Logical API errors throw stable codes so users see translated messages instead of a generic bad request.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/common/errors/validation-exception.factory.ts

@@ -1,4 +1,4 @@
-import { BadRequestException, HttpException, HttpStatus } from '@nestjs/common';
+import { HttpException, HttpStatus } from '@nestjs/common';
 import type { ValidationError } from 'class-validator';
 import { AppException } from './app.exception';
 import { ErrorCode, type ErrorCodeValue, type ValidationErrorDetail } from './error-codes';
@@ -22,7 +22,12 @@ function constraintToCode(constraintKey: string, message: string): ErrorCodeValu
     case 'isEnum':
       return ErrorCode.VALIDATION_ORGANIZATION_TYPE_INVALID;
     case 'matches':
-      return ErrorCode.VALIDATION_MOBILE_INVALID;
+    case 'isDateString':
+    case 'isUuid':
+    case 'isInt':
+    case 'isBoolean':
+    case 'isArray':
+      return ErrorCode.VALIDATION_INVALID_REQUEST;
     case 'isIn':
       return ErrorCode.VALIDATION_LANGUAGE_INVALID;
     case 'whitelistValidation':
@@ -66,8 +71,3 @@ export function validationExceptionFactory(errors: ValidationError[]): HttpExcep
 
   return new AppException(ErrorCode.VALIDATION_FAILED, HttpStatus.BAD_REQUEST, details);
 }
-
-/** Handles forbidNonWhitelisted errors from ValidationPipe. */
-export function isValidationPipeBadRequest(exception: unknown): exception is BadRequestException {
-  return exception instanceof BadRequestException;
-}