feat(inbox): Enable conversation continuity for social channels (#11079)

## Summary
This PR enables and surfaces **conversation workflow** for social-style
channels that should support either:
- `Create new conversations` after resolve, or
- `Reopen same conversation`

## What is included
- Adds the conversation workflow setting UI as card-based options in
Inbox Settings.
- Expands channel availability in settings to include channels like:
  - Telegram
  - TikTok
  - Instagram
  - Line
  - WhatsApp
  - Facebook
- Updates conversation selection behavior for Line incoming messages to
respect the workflow (reopen vs create-new-after-resolved).
- Updates TikTok conversation selection behavior to respect the workflow
(reopen vs create-new-after-resolved).
- Keeps email behavior unchanged (always starts a new thread).

Fixes: https://github.com/chatwoot/chatwoot/issues/8426

## Screenshot

<img width="1400" height="900" alt="pr11079-workflow-sender-clear-tight"
src="https://github.com/user-attachments/assets/9456821f-8d83-4924-8dcf-7503c811a7b1"
/>


## How To Reproduce
1. Open `Settings -> Inboxes ->
<Telegram/TikTok/Instagram/Line/Facebook/WhatsApp inbox> -> Settings`.
2. Verify **Conversation workflow** is visible with the two card
options.
3. Toggle between both options and save.
4. For Line and TikTok, verify resolved-conversation behavior follows
the selected workflow.

## Testing
- `RAILS_ENV=test bundle exec rspec
spec/builders/messages/instagram/message_builder_spec.rb:213
spec/builders/messages/instagram/message_builder_spec.rb:255
spec/builders/messages/instagram/messenger/message_builder_spec.rb:228
spec/builders/messages/instagram/messenger/message_builder_spec.rb:293
spec/services/tiktok/message_service_spec.rb`
- Result: `16 examples, 0 failures`

## Follow-up
- Migrate Website Live Chat workflow settings into this same
conversation-workflow settings model.
- Add Voice channel support for this workflow setting.

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>

spec/services/tiktok/message_service_spec.rb

@@ -6,8 +6,29 @@ RSpec.describe Tiktok::MessageService do
   let(:inbox) { channel.inbox }
   let(:contact) { create(:contact, account: account) }
   let(:contact_inbox) { create(:contact_inbox, inbox: inbox, contact: contact, source_id: 'tt-conv-1') }
+  let(:text_content) do
+    {
+      type: 'text',
+      message_id: 'tt-msg-lock',
+      timestamp: 1_700_000_000_000,
+      conversation_id: 'tt-conv-1',
+      text: { body: 'Hello from TikTok' },
+      from: 'Alice',
+      from_user: { id: 'user-1' },
+      to: 'Biz',
+      to_user: { id: 'biz-123' }
+    }.deep_symbolize_keys
+  end
 
   describe '#perform' do
+    subject(:perform_text_message) do
+      service = described_class.new(channel: channel, content: current_content)
+      allow(service).to receive(:create_contact_inbox).and_return(contact_inbox)
+      service.perform
+    end
+
+    let(:current_content) { text_content }
+
     it 'creates an incoming text message' do
       content = {
         type: 'text',
@@ -113,5 +134,31 @@ RSpec.describe Tiktok::MessageService do
     ensure
       tempfile.close!
     end
+
+    context 'when lock_to_single_conversation is enabled' do
+      it 'reuses the last resolved conversation' do
+        inbox.update!(lock_to_single_conversation: true)
+        resolved_conversation = create(:conversation, inbox: inbox, contact: contact, contact_inbox: contact_inbox, status: :resolved)
+
+        perform_text_message
+
+        expect(inbox.conversations.count).to eq(1)
+        expect(resolved_conversation.reload.messages.last.content).to eq('Hello from TikTok')
+      end
+    end
+
+    context 'when lock_to_single_conversation is disabled' do
+      let(:current_content) { text_content.merge(message_id: 'tt-msg-lock-2') }
+
+      it 'creates a new conversation if the previous one is resolved' do
+        inbox.update!(lock_to_single_conversation: false)
+        create(:conversation, inbox: inbox, contact: contact, contact_inbox: contact_inbox, status: :resolved)
+
+        perform_text_message
+
+        expect(inbox.conversations.count).to eq(2)
+        expect(inbox.conversations.last.messages.last.content).to eq('Hello from TikTok')
+      end
+    end
   end
 end