chore(align): sync Git with running container as authoritative source

Phase 0 SSE 流式聊天 landed in the running container and captured in Git so
the three sources (container := image := Git) agree.

Phase 0 — SSE 流式聊天（Web 端，IM bot 路径保持不变、共用引擎）:
- app/api/chat.py: 新增独立 SSE 端点
  POST /app/api/chat/conversations/{conv_id}/messages/stream
  基于 asyncio.Queue + create_task 将 _send_message_core 桥接为
  text/event-stream 生成器，吐出 delta / reasoning / done / error 事件
- app/api/chat_service.py: _send_message_core 增加 stream + on_event 参数；
  普通（无工具）聊天 round-0 主调用走 achat_complete(stream=True) 流式；
  done 事件携带 message_id / content / process_steps / used_skills /
  used_mcp / generating
- app/core/llm_client.py: 修复 _create_kwargs 硬编码 stream=False 的根因 bug
  （流式调用传 stream=True 导致 TypeError: multiple values for keyword），
  现 _create_kwargs(request_body, stream=True) 字段随参数变化
- frontend/src/pages/front/ChatPage.tsx + ChatPage.css + types/index.ts:
  发消息改为 fetch SSE 消费，实时增量渲染 AI 回复文本与思考链(reasoning)，
  done 事件用 message_id 定稿并渲染过程步骤；网络/流式失败自动回退非流式

Alignment performed 2026-07-24 18:25:11. No deletions; secrets/venv/node_modules/
caches were not touched (tracked-source-only copy).

backend/python/app/api/chat_service.py

@@ -1999,6 +1999,15 @@ async def _send_message_core(
 
     process_steps = []  # 过程步骤(思考/技能/MCP执行)，用于前端收拢式展示
 
+    async def _push_step(step: dict):
+        """追加过程步骤，并在流式场景实时推送给前端(step 事件)。"""
+        await _push_step(step)
+        if on_event is not None:
+            try:
+                await on_event({"type": "step", "step": step, "index": len(process_steps) - 1})
+            except Exception:
+                pass
+
 
 
 
@@ -4489,7 +4498,7 @@ async def _send_message_core(
 
                             })
 
-                            process_steps.append({
+                            await _push_step({
 
                                 "type": "skill",
 
@@ -4791,10 +4800,11 @@ async def _send_message_core(
 
                                 try:
 
-                                    if stream and on_event is not None and round_num == 0 and not (effective_mcp_ids or effective_skill_ids or effective_agent_ids):
+                                    if stream and on_event is not None:
 
                                         _sc = ""
                                         _sr = ""
+                                        _final_msg = None
                                         async for _kind, _text in await achat_complete(
                                             api_url, api_key, request_body,
                                             proxy=_proxy_for_url(api_url),
@@ -4807,7 +4817,15 @@ async def _send_message_core(
                                             elif _kind == "reasoning":
                                                 _sr += _text
                                                 await on_event({"type": "reasoning", "content": _text})
-                                        message = {"content": _sc, "tool_calls": [], "reasoning": _sr}
+                                            elif _kind == "message":
+                                                _final_msg = _text
+                                        if _final_msg is not None:
+                                            _final_msg = dict(_final_msg)
+                                            if "reasoning_content" in _final_msg:
+                                                _final_msg["reasoning"] = _final_msg.pop("reasoning_content")
+                                            message = _final_msg
+                                        else:
+                                            message = {"content": _sc, "tool_calls": [], "reasoning": _sr}
                                         choice = {"message": message}
                                         data = {"choices": [choice], "usage": {}}
                                     else:
@@ -4983,7 +5001,7 @@ async def _send_message_core(
 
                                 if _think and tool_calls:
 
-                                    process_steps.append({
+                                    await _push_step({
 
                                         "type": "thinking",
 
@@ -5469,7 +5487,7 @@ async def _send_message_core(
 
                                                     called_mcp_names.append(_srv.get("name", ""))
 
-                                                process_steps.append({
+                                                await _push_step({
 
                                                     "type": "mcp",
 
@@ -5545,7 +5563,7 @@ async def _send_message_core(
 
                                                 called_skill_names.append(_sk.get("name", ""))
 
-                                            process_steps.append({
+                                            await _push_step({
 
                                                 "type": "skill",