Workspace: starring a chat fails on the first click, works on the second #3356

Summary

Starring a chat in the Workspace does not work on the first try. The first click on the star does not pin the chat. A second click does.

Steps to reproduce

1. Open the Workspace and pick a chat that is not starred.
2. Click its star (on the sidebar row or in the conversation header).
3. Observed: the chat is not starred. It does not move to the Starred section, or the star does not stay filled.
4. Click the star again.
5. Observed: now the chat is starred.

Expected: one click stars the chat, and it shows in the Starred section straight away.

Context

Found by a maintainer using the Workspace (2026-10-08). Starring is how users pin the chats they return to, and the composer star control planned next would inherit this bug. A star that needs two clicks reads as broken.

Acceptance Criteria

• A single click stars an unstarred chat, and a single click unstars a starred one, from every star control (sidebar row, Starred section, conversation header).
• The state survives a page reload (it is saved, not only shown).
• Holds for a chat that was just created and for a chat opened for the first time in this session.
• A regression test covers the first click on a never-starred chat.

Technical Notes

Star controls: src/frontend/src/components/portal/PortalStarButton.vue, used by PortalChatRow.vue and PortalConversation.vue.