fix(widget): validate required checkboxes as accepted (#15135)

Required checkbox fields in the pre-chat form now remain invalid unless
they are checked. Other required field types keep their existing
validation behavior, and the existing localized required message is
reused.

## Closes

Closes https://github.com/chatwoot/chatwoot/issues/15128

## How to reproduce

1. Add a required checkbox custom attribute to the pre-chat form.
2. Check and then uncheck it.
3. Submit the form; submission is now blocked until the checkbox is
checked.

## What changed

- Use the FormKit accepted rule for required checkbox fields.
- Map accepted validation failures to the existing pre-chat required
message.

---------

Co-authored-by: Nazmus Samir <nazmussamir@Nazmuss-MacBook-Pro.local>
Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/javascript/widget/components/PreChat/Form.vue

@@ -187,7 +187,8 @@ export default {
       };
       const validationKeys = Object.keys(validations);
       const isRequired = this.isContactFieldRequired(name);
-      const baseRules = isRequired ? [['required']] : [['optional']];
+      const requiredRule = type === 'checkbox' ? 'accepted' : 'required';
+      const baseRules = isRequired ? [[requiredRule]] : [['optional']];
 
       if (
         !validationKeys.includes(name) &&
@@ -293,6 +294,7 @@ export default {
         isValidPhoneNumber: $t('PRE_CHAT_FORM.FIELDS.PHONE_NUMBER.VALID_ERROR'),
         email: $t('PRE_CHAT_FORM.FIELDS.EMAIL_ADDRESS.VALID_ERROR'),
         required: $t('PRE_CHAT_FORM.REQUIRED'),
+        accepted: $t('PRE_CHAT_FORM.REQUIRED'),
         matches: item.regex_cue
           ? item.regex_cue
           : $t('PRE_CHAT_FORM.REGEX_ERROR'),

app/javascript/widget/components/PreChat/specs/Form.spec.js

@@ -0,0 +1,39 @@
+import { describe, expect, it } from 'vitest';
+
+import Form from '../Form.vue';
+
+const getValidation = Form.methods.getValidation;
+
+const validationFor = (field, required) =>
+  getValidation.call(
+    {
+      isContactFieldRequired: () => required,
+    },
+    field
+  );
+
+describe('PreChat Form getValidation', () => {
+  it('returns accepted for a required checkbox', () => {
+    expect(validationFor({ type: 'checkbox', name: 'checkbox' }, true)).toEqual(
+      [['accepted']]
+    );
+  });
+
+  it('returns optional for an optional checkbox', () => {
+    expect(
+      validationFor({ type: 'checkbox', name: 'checkbox' }, false)
+    ).toEqual([['optional']]);
+  });
+
+  it('returns required for a required text field', () => {
+    expect(validationFor({ type: 'text', name: 'text' }, true)).toEqual([
+      ['required'],
+    ]);
+  });
+
+  it('combines required and type-specific validation rules', () => {
+    expect(
+      validationFor({ type: 'email', name: 'emailAddress' }, true)
+    ).toEqual([['required'], ['email']]);
+  });
+});