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/controllers/api/v1/accounts/tiktok/authorizations_controller_spec.rb

@@ -32,23 +32,25 @@ RSpec.describe 'TikTok Authorization API', type: :request do
       end
 
       it 'creates a new authorization and returns the redirect url' do
-        with_modified_env TIKTOK_APP_ID: 'tiktok-app-id', TIKTOK_APP_SECRET: 'tiktok-app-secret' do
-          post "/api/v1/accounts/#{account.id}/tiktok/authorization",
-               headers: administrator.create_new_auth_token,
-               as: :json
+        travel_to Time.zone.parse('2025-01-01 00:00:00 UTC') do
+          with_modified_env TIKTOK_APP_ID: 'tiktok-app-id', TIKTOK_APP_SECRET: 'tiktok-app-secret' do
+            post "/api/v1/accounts/#{account.id}/tiktok/authorization",
+                 headers: administrator.create_new_auth_token,
+                 as: :json
+          end
+
+          expect(response).to have_http_status(:success)
+          expect(response.parsed_body['success']).to be true
+
+          helper = Class.new do
+            include Tiktok::IntegrationHelper
+          end.new
+
+          expected_state = helper.generate_tiktok_token(account.id)
+          expected_url = Tiktok::AuthClient.authorize_url(state: expected_state)
+
+          expect(response.parsed_body['url']).to eq(expected_url)
         end
-
-        expect(response).to have_http_status(:success)
-        expect(response.parsed_body['success']).to be true
-
-        helper = Class.new do
-          include Tiktok::IntegrationHelper
-        end.new
-
-        expected_state = helper.generate_tiktok_token(account.id)
-        expected_url = Tiktok::AuthClient.authorize_url(state: expected_state)
-
-        expect(response.parsed_body['url']).to eq(expected_url)
       end
     end
   end