feat(message): show past chat references and files in user message bubble

[SuMuxi66]

概述

本 PR 是 #3336 合并后的 follow-up。

#3336 已经完成 past:chats 的选择、预览和上下文注入流程。本 PR 只补充发送后的展示能力：当用户消息引用了历史会话时，在用户消息气泡中展示对应的引用卡片。

改动内容

• 将已选中的 past:chats references 随用户消息一起传入 transcript
• 用户消息支持携带并渲染 references
• 在用户消息气泡中展示历史会话引用卡片
• 引用卡片展示会话标题、消息数量、文件名等信息
• 调整用户消息气泡和引用卡片样式

范围说明

本 PR 只处理“发送后如何展示引用”的问题。

不修改：

• past:chats 菜单选择逻辑
• 历史会话预览逻辑
• 上下文注入逻辑
• @ 文件引用逻辑

验证

• 基于已合并的 feat(composer): add past chats reference flow #3336
• 发送带 past:chats 引用的消息后，用户消息气泡中可以看到引用卡片
• 未引用历史会话的普通用户消息显示正常
• 文件引用流程不受影响

[SivanCola]

Thanks, this is directionally useful, but I cannot approve it yet.

Required changes:

• The send path waits for PreviewSession/buildSessionContext before calling onSend or clearing the composer. While that await is pending, the input and send button remain enabled, so pressing Enter or clicking send again can submit duplicate turns with the same referenced sessions. It also breaks the PR's stated "display immediately after send" behavior for referenced sends. Please snapshot/lock/clear the composer before the async session reads, or add an explicit sending guard that makes duplicate submission impossible.

• The new past:chats UI is not wired into the existing keyboard menu state. menuMode only opens the @ menu when atMatches.length > 0, count still excludes the special/session rows, and pickActive() always calls pickEntry(atMatches[active]). This means the past-chat option can disappear when there are no file matches, and Enter/Tab cannot select a highlighted past-chat session. Please make past-chat rows first-class menu items for open/active/count/pick handling.

• New visible UI strings are hard-coded in Chinese in Composer.tsx and Message.tsx. The desktop frontend has an existing en/zh dictionary contract, so English locale users will see mixed Chinese. Please add the required i18n keys in both locale files and use t(...)/useT() for visible text.

• git diff --check origin/main-v2...origin/pr/3338 currently fails because docs/SESSION_REFERENCE_ARCHITECTURE.md contains trailing whitespace. Please clean that up before merge.

Integration notes:

• This PR is still draft and stacked on #3336; it should be rebased after the core past-chats PR is finalized.
• It also overlaps #3356 on user-message bubble styling, so one of the two PRs should become the integration source for that layout.

Verified locally:

• wails generate module passed after creating the expected temporary frontend/dist placeholder in a throwaway worktree.
• npm run build passed in desktop/frontend.
• go test . -run 'TestPreviewSession|TestListSessions|TestHistory|TestSession' passed in desktop.
• git merge-tree --write-tree origin/main-v2 origin/pr/3338 produced an auto-merge tree with no textual conflicts.

[SivanCola]

Thanks for the follow-up changes. I re-reviewed the current head and the earlier blockers around duplicate sends, menu state, i18n, and diff --check look addressed now.

I still found a couple of issues that should be fixed before merge:

• The referenced-session cards are not persisted. send() only passes references into the frontend reducer, while the backend history/display sidecar still stores only strings, and historyMessagesToItems() rebuilds user messages without references. So the cards appear right after sending, but disappear after reload/resume/history replay. Please persist the structured session refs alongside the display content and restore them when mapping history back to Items.

• Message.tsx wraps a block <div className="msg__reference-item"> inside Tooltip, which defaults to a <span> trigger. That creates invalid DOM / React nesting warnings and can affect layout. Please use the Tooltip block mode here or change the child to an inline-compatible element.

• A selected past-chat reference alone cannot be sent: the submit guard and send-button disabled condition still only count text, attachments, and workspace refs. If a session ref is meant to be usable as context by itself, include sessionRefs.length in those checks; if not, the UI should make the “question required” state explicit instead of showing an attached chip with a disabled send button.

Verified: git diff --check origin/main-v2...origin/pr/3338 passes on the current PR head.

[SuMuxi66]

感谢 review，我已经按反馈修复了这三个 blocker。

本次更新：

• "past:chats" references 现在会通过 ".references.json" sidecar 持久化，模式和现有 ".display.json" sidecar 保持一致。
• "HistoryForTab()" 和 history-to-transcript 映射现在会恢复 references，所以刷新、继续会话、历史回放后，用户消息里的引用卡片不会丢失。
• references 卡片块现在位于 ".msg__body" 下，不再嵌套进 Markdown paragraph / "

  " 内，避免非法 DOM 结构。

• submit guard 和 send button disabled 逻辑都已加入 "sessionRefs.length === 0" 判断，因此只选择 past chat reference、正文为空时也可以发送。

验证结果：

• reload 测试通过：浏览器刷新后，引用卡片仍然显示。
• DOM 检查通过：reference card 的父节点是 ".msg__body"。
• console 检查通过：没有前端错误。
• "git diff --check" 通过。
• Go 端 "go build"、"go vet" 和相关 history / preview 测试通过。
• full frontend "tsc" 目前仍被既有的 "VirtualMenu.tsx" / "@tanstack/react-virtual" 依赖问题阻塞；本 PR 没有在改动文件中引入新的 TypeScript 错误。