Remote friend Bot mention from the "@" menu renders as a raw handle, not a Bot mention (bubble + sidebar preview) #71

Part of #5 (@flybot/social); display side of the #9 umbrella (display names).

Environment

• macOS arm64, FlyBot core + @flybot/social from ThinkFlowLab/FlyBot#main (a48fd86), dsh web UI.
• A group chat (You, Chief, 代码审查官, FlyBot Manager) whose members include the Friends' remote Bot 代码审查官 (@bot-2a758c0f.danyang.home, home danyang.home).

Steps to reproduce

1. In the group chat, type @ and pick the remote Bot from the menu (its row shows "代码审查官 (bot-2a758c0f.danyang.home) · Remote · danyang.home").
2. Finish the message, e.g. 你是?, and send.
3. Look at the group's row in the sidebar, and at the sent bubble.

Actual

Picking a remote Bot inserts its raw handle as text (remoteMentionRows inserts @<handle> ), so the stored message is:

@bot-2a758c0f.danyang.home 你是?

• The sidebar conversation preview shows that raw address: @bot-2a758c0f.danyang.home 你是? (see screenshot).
• In the chat bubble the handle is not a Bot mention: the client mention rule matches display names only (shared/mentions.js), and remote Bots are not in the roster's bot list (mentionableBots maps room members through roster.byId). So the handle falls through to DSH's generic user-text rendering — which, per the comment at the top of user-message.js, draws every @word as a file reference. Team Bot mentions in the same chat (@代码审查官, @FlyBot Manager — the first two bubbles in the screenshot) render as avatar + name chips; the remote one renders as a file-like address.

Delivery itself works: the host's sendUserMentions recognizes @<handle> and sends it through bot.send (social approval still applies), so this is display-only.

Expected

• The bubble renders the remote mention like any Bot mention: avatar + display name (代码审查官), clickable to that Bot's remote chat.
• The sidebar preview shows a readable mention (@代码审查官 你是?), not the endpoint address.

Where it sits (for discussion, not prescriptive)

• core/src/client/flybot-registry.js remoteMentionRows — inserts @handle .
• core/src/client/at-menu.js mentionRows — merges those rows into every chat's @ menu.
• core/src/client/user-message.js userTextParts — chips only display-name matches; handles fall through to DSH's file-reference rendering.
• core/src/client/text.js previewOf — preview shows the stored text as-is.
• core/src/host/hooks.js sendUserMentions — already matches the handle form (name = handle without @), which is what keeps delivery working.

The display name would need to come from the local remote-members record (roster.remoteBots), never from message text, so the display-name trust rule in #9 stays intact.

Screenshot