feat: allow agent bots to toggle typing status (#13705)

Agent bot conversations now feel more natural because AgentBot tokens
can toggle typing status, so end users see a live typing indicator in
the widget while the bot is preparing a reply. This keeps the
interaction responsive and human-like without weakening token
authorization boundaries.

## Closes
- https://github.com/chatwoot/chatwoot/issues/8928
- https://linear.app/chatwoot/issue/CW-5205

## How to test
1. Open the widget and start a conversation as a customer.
2. Connect an AgentBot to the same inbox.
3. Trigger `toggle_typing_status` with the AgentBot token
(`typing_status: on`).
4. Confirm the customer sees the typing indicator in the widget.
5. Trigger `toggle_typing_status` with `typing_status: off` and confirm
the indicator disappears.

## What changed
- Added `toggle_typing_status` to bot-accessible conversation endpoints.
- Restricted bot-accessible endpoint usage to `AgentBot` token owners
only (non-user tokens like `PlatformApp` remain unauthorized).
- Updated typing status flow to preserve AgentBot identity in
dispatch/broadcast paths.
- Added request coverage for AgentBot success and PlatformApp
unauthorized behavior.
- Added Swagger documentation for `POST
/api/v1/accounts/{account_id}/conversations/{conversation_id}/toggle_typing_status`
and regenerated swagger artifacts.

swagger/paths/index.yml

@@ -367,6 +367,12 @@
     - $ref: '#/components/parameters/conversation_id'
   post:
     $ref: ./application/conversation/toggle_priority.yml
+/api/v1/accounts/{account_id}/conversations/{conversation_id}/toggle_typing_status:
+  parameters:
+    - $ref: '#/components/parameters/account_id'
+    - $ref: '#/components/parameters/conversation_id'
+  post:
+    $ref: ./application/conversation/toggle_typing_status.yml
 
 /api/v1/accounts/{account_id}/conversations/{conversation_id}/custom_attributes:
   parameters: