chat: 持久化继续消息，chat-history 交替历史

基线 main 811912c（PR #125 Muse 风格之后）：服务端与单测与
9538825 相同；React 侧在 Muse 风格 ContinuePanel 上重放
chat-history 集成（新版输入框占位文案保持 Muse 风格的“消息”），
console.html 由新版 src 重新构建。

- 新表 task_continue_messages：POST /continue 的用户消息与状态改回
  queued 同一事务落盘，409 被拒不留 phantom 消息
- GET /tasks/{id}/chat-history：prompt + 继续 + 后续消息 + 链路按
  时间交错拼好返回；部署前继续以 legacy_continue_count 如实标注
- React ContinuePanel 优先用 chat-history，旧服务端自动回退

cloud/console-react/src/hooks/useConsoleStore.ts

@@ -126,6 +126,7 @@ export function useConsoleStore(): ConsoleCtx {
     traceEntries: detail.traceEntries, traceNote: detail.traceNote, traceDone: detail.traceDone,
     traceKind: detail.traceKind, setTraceKind: detail.setTraceKind, downloadTrace: detail.downloadTrace, traceMsg: detail.traceMsg,
     sendChatMessage: detail.sendChatMessage, chatMsg: detail.chatMsg,
+    chatHistory: detail.chatHistory,
     followups: detail.followups,
     approvals: detail.approvals, approvalMsg: detail.approvalMsg, refreshApprovals: detail.refreshApprovals, decideApproval: detail.decideApproval,
     peerMessages: detail.peerMessages, peerMsg: detail.peerMsg, postPeer: detail.postPeer,