Sync: threads panel after replying to a message

The user replies to a message in the main feed and opens the «Threads» panel: the header and list area are displayed (the list may be empty if thread_id is not yet set on feed messages).

Step 1. Space and channel created¶

Step 2. Root message sent¶

Step 3. Thread opened and reply sent¶

Step 4. Threads panel opened¶