fix: Block inline images in message signatures (#13772)

# Pull Request Template

## Description

This PR includes, block inline images in message signatures and prevent
auto signature insertion when editor is disabled.

- Strip inline base64 images from signature on save and show warning
message
- Add `INLINE_IMAGE_WARNING` translation key for signature inline image
removal notification
- Add disabled check to `addSignature()` to prevent signature insertion
when editor is disabled
- Add `isEditorDisabled` checks to signature toggle logic in
`toggleSignatureForDraft()`, `replaceText()`, and `clearMessage()`
- Remove unused `replaceText` from the codebase, which belongs to old
`textarea` editor

Fixes
https://linear.app/chatwoot/issue/CW-6588/the-browser-hangs-when-the-message-signature-contains-inline-image

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

### Loom video
https://www.loom.com/share/fb556b46a12a4308a737eed732d5ed73


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/javascript/dashboard/routes/dashboard/settings/profile/MessageSignature.vue

@@ -1,5 +1,8 @@
 <script setup>
 import { ref, watch } from 'vue';
+import { useI18n } from 'vue-i18n';
+import { useAlert } from 'dashboard/composables';
+import { stripInlineBase64Images } from 'dashboard/helper/editorHelper';
 import WootMessageEditor from 'dashboard/components/widgets/WootWriter/Editor.vue';
 import NextButton from 'dashboard/components-next/button/Button.vue';
 
@@ -11,7 +14,9 @@ const props = defineProps({
 });
 
 const emit = defineEmits(['updateSignature']);
-const signature = ref(props.messageSignature);
+
+const { t } = useI18n();
+const signature = ref(props.messageSignature ?? '');
 watch(
   () => props.messageSignature ?? '',
   newValue => {
@@ -20,6 +25,15 @@ watch(
 );
 
 const updateSignature = () => {
+  const { sanitizedContent, hasInlineImages } = stripInlineBase64Images(
+    signature.value || ''
+  );
+  signature.value = sanitizedContent.trim();
+  if (hasInlineImages) {
+    useAlert(
+      t('PROFILE_SETTINGS.FORM.MESSAGE_SIGNATURE_SECTION.INLINE_IMAGE_WARNING')
+    );
+  }
   emit('updateSignature', signature.value);
 };
 </script>