chore: Default file limits for private notes and reset attachment on mode switch (#12310)

# Pull Request Template

## Description

This PR fixes the handling of attachments and file limits in reply
modes:

* Applies **default file size and type limits** for private notes
* **Resets attachments** automatically when switching reply modes


## 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/abad3e6a0383405ea5f31314c1494f2f?sid=38715fd0-e305-4a9b-8f4d-fc6a6e5c0833


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] 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/components/widgets/WootWriter/ReplyBottomPanel.vue

@@ -7,6 +7,7 @@ import * as ActiveStorage from 'activestorage';
 import inboxMixin from 'shared/mixins/inboxMixin';
 import { FEATURE_FLAGS } from 'dashboard/featureFlags';
 import { getAllowedFileTypesByChannel } from '@chatwoot/utils';
+import { ALLOWED_FILE_TYPES } from 'shared/constants/messages';
 import VideoCallButton from '../VideoCallButton.vue';
 import AIAssistanceButton from '../AIAssistanceButton.vue';
 import { REPLY_EDITOR_MODES } from './constants';
@@ -151,6 +152,11 @@ export default {
       uploadRef,
     };
   },
+  data() {
+    return {
+      ALLOWED_FILE_TYPES,
+    };
+  },
   computed: {
     ...mapGetters({
       accountId: 'getCurrentAccountId',
@@ -192,6 +198,11 @@ export default {
       return this.conversationType === 'instagram_direct_message';
     },
     allowedFileTypes() {
+      // Use default file types for private notes
+      if (this.isOnPrivateNote) {
+        return this.ALLOWED_FILE_TYPES;
+      }
+
       let channelType = this.channelType || this.inbox?.channel_type;
 
       if (this.isAnInstagramChannel || this.isInstagramDM) {