feat: Enable lock to single thread settings for Telegram (#12367)

This PR implements the **"Lock to Single Conversation"** option for
Telegram inboxes, bringing it to parity with WhatsApp, SMS, and other
channels.

- When **enabled**: resolved conversations can be reopened (single
thread).
- When **disabled**: new messages from a resolved conversation create a
**new conversation**.
- Added **agent name display** in outgoing Telegram messages (formatted
as `Agent Name: message`).
- Updated frontend to display agent name above messages in the dashboard
(consistent with WhatsApp behavior).

This fixes [#8046](https://github.com/chatwoot/chatwoot/issues/8046).

## Type of change

Please delete options that are not relevant.

- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality not to work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

- Unit tests added in
`spec/services/telegram/incoming_message_service_spec.rb`
- Scenarios covered:
  - Lock enabled → reopens resolved conversation
  - Lock disabled → creates new conversation if resolved
  - Lock disabled → appends to last open conversation
- Manual tests:
  1. Create a Telegram conversation
  2. Mark it as resolved
  3. Send a new message from same user
  4. ✅ Expected: new conversation created (if lock disabled)


## 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
- [ ] My changes generate no new warnings
- [x] 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

## Additional Documentation

For full technical details of this implementation, please refer to:  

[TELEGRAM_LOCK_TO_SINGLE_CONVERSATION_IMPLEMENTATION_EN.md](./TELEGRAM_LOCK_TO_SINGLE_CONVERSATION_IMPLEMENTATION_EN.md)

---------

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

app/javascript/dashboard/routes/dashboard/settings/inbox/Settings.vue

@@ -206,7 +206,8 @@ export default {
         this.isASmsInbox ||
         this.isAWhatsAppChannel ||
         this.isAFacebookInbox ||
-        this.isAPIInbox
+        this.isAPIInbox ||
+        this.isATelegramChannel
       );
     },
     inboxNameLabel() {

app/services/telegram/incoming_message_service.rb

@@ -77,7 +77,13 @@ class Telegram::IncomingMessageService
   end
 
   def set_conversation
-    @conversation = @contact_inbox.conversations.first
+    # if lock to single conversation is disabled, we will create a new conversation if previous conversation is resolved
+    @conversation = if @inbox.lock_to_single_conversation
+                      @contact_inbox.conversations.last
+                    else
+                      @contact_inbox.conversations
+                                    .where.not(status: :resolved).last
+                    end
     return if @conversation
 
     @conversation = ::Conversation.create!(conversation_params)