fix(botops): resolve duplicate AI response rendering in ChatView

Root cause: aibox.py think_and_respond recursively calls itself after tool
execution, and each recursive call's complete callback carries only the
final-round full_response. The old finish_ai logic treated complete as a
full-text alignment signal — when full_text != self._ai_text (which always
happened after recursive tool calls because _ai_text accumulated all chunks
while complete only held the last round), it triggered remove+remount,
causing visible duplicate/flash of AI responses. A secondary issue was
dialogue_ended arriving before complete, which made a second finish_ai call
remount the message a second time.

Changes:
- Remove the full-text replacement branch in finish_ai; chunk streaming is
  now the authoritative content source, complete is a finalization signal only
- Add _ai_finalized flag: start_ai resets it, finish_ai sets it; repeated
  finish_ai calls (dialogue_ended + complete) return early to prevent remount
- append_ai drops late chunks after finalization to avoid dirty appends
- Empty pre-built widget without chunks still gets filled via w.update(full_text)
- Full lost-frame fallback (no widget + full_text) is preserved
- Update BotOps/README.md protocol section to reflect new complete semantics

BotOps/README.md

@@ -58,4 +58,9 @@ BotOps/
 
 与 aibox 服务端协议完全兼容（详见 aibox/client.py 注释）：
 - 发送：`{"type":"message","content":...}` / `{"type":"command","command":"/..."}` / `{"type":"interrupt",...}`
-- 接收：`chunk`（**增量片段**，服务端 `chunk_buffer` 发送后即清零，前端直接拼接）/ `complete`（**完整全文**，用于对齐已显示内容）/ `line`（过程行：🔧 工具调用提示、工具输出、💬 助手前缀，路由到任务侧栏）/ `reasoning`（思考流，仅服务端 debug_level≥3 发送）/ `dialogue_ended` / `dialogue_reset` / `task_added` / `task_process` / `task_status` / `task_error` / `interrupt_ack` / `error` / `info` / `command_result` / `connection_ack` / `notification` / `pong`
+- 接收：
+  - `chunk`（**增量片段**）：服务端 `chunk_buffer` 发送后即清零，前端直接 `append_ai` 拼接，为内容权威来源
+  - `complete`（**收尾信号**）：chunk 流式已完整渲染，complete 仅用于收尾；仅在完全丢帧（未收到任何 chunk）时用 full_text 补建消息，**不再做全文替换对齐**（避免服务端递归调用工具后 complete 只含最后一轮内容导致重复渲染）
+  - `line`（过程行）：🔧 工具调用提示、工具输出、💬 助手前缀，路由到任务侧栏；助手前缀/思考提示在聊天区已由 AI 消息框承载，不重复展示
+  - `reasoning`（思考流）：仅服务端 debug_level≥3 发送，记入任务侧栏
+  - `dialogue_ended` / `dialogue_reset` / `task_added` / `task_process` / `task_status` / `task_error` / `interrupt_ack` / `error` / `info` / `command_result` / `connection_ack` / `notification` / `pong`