feat: 将项目从nano重命名为beaver并更新相关配置

- 将所有环境变量前缀从NANO_改为BEAVER_
- 更新README.md文档内容，包括项目介绍、组件说明和快速开始指南
- 修改.gitignore文件，添加auth-portal运行时路径排除规则
- 更新app-instance镜像标签从nano/app-instance改为beaver/app-instance
- 增强技能安全检查器，支持工具前缀白名单功能
- 添加技能草稿重新检查安全性API端点
- 扩展证据选择器，收集工具调用名称用于技能学习
- 改进技能合成器，基于实际调用的工具生成工具提示
- 优化路由超时处理机制，增加重试逻辑
- 更新后端架构文档，添加可视化入口和基础概念说明
- 实现在WebSocket消息中传递工具迭代次数信息

app-instance/backend/beaver/tasks/router.py

@@ -26,38 +26,42 @@ class MainAgentRouter:
     ) -> MainAgentDecision:
         if provider is None:
             return self._fallback(active_task=active_task, reason="router_provider_unavailable")
-        try:
-            chat_kwargs: dict[str, Any] = {
-                "messages": [
-                    {
-                        "role": "system",
-                        "content": (
-                            "You are Beaver's Intent Agent. Your only job is to route the user's "
-                            "message to simple chat or internal Task mode. Return only compact JSON. "
-                            "Do not answer the user. Do not explain."
-                        ),
-                    },
-                    {
-                        "role": "user",
-                        "content": self._prompt(
-                            message=message,
-                            active_task=active_task,
-                            recent_messages=recent_messages or [],
-                            intent_skill=intent_skill,
-                        ),
-                    },
-                ],
-                "tools": None,
-                "model": model,
-                "max_tokens": 256,
-                "temperature": 0.0,
-            }
-            if thinking_enabled is not None:
-                chat_kwargs["thinking_enabled"] = thinking_enabled
-            response = await asyncio.wait_for(provider.chat(**chat_kwargs), timeout=timeout_seconds)
-            return self.from_json(response.content or "", active_task=active_task)
-        except Exception as exc:
-            return self._fallback(active_task=active_task, reason=f"router_failed: {exc}")
+        chat_kwargs: dict[str, Any] = {
+            "messages": [
+                {
+                    "role": "system",
+                    "content": (
+                        "You are Beaver's Intent Agent. Your only job is to route the user's "
+                        "message to simple chat or internal Task mode. Return only compact JSON. "
+                        "Do not answer the user. Do not explain."
+                    ),
+                },
+                {
+                    "role": "user",
+                    "content": self._prompt(
+                        message=message,
+                        active_task=active_task,
+                        recent_messages=recent_messages or [],
+                        intent_skill=intent_skill,
+                    ),
+                },
+            ],
+            "tools": None,
+            "model": model,
+            "max_tokens": 256,
+            "temperature": 0.0,
+        }
+        if thinking_enabled is not None:
+            chat_kwargs["thinking_enabled"] = thinking_enabled
+
+        last_error: Exception | None = None
+        for attempt_timeout in (timeout_seconds, 12.0):
+            try:
+                response = await asyncio.wait_for(provider.chat(**chat_kwargs), timeout=attempt_timeout)
+                return self.from_json(response.content or "", active_task=active_task)
+            except Exception as exc:
+                last_error = exc
+        return self._fallback(active_task=active_task, reason=f"router_failed: {last_error}")
 
     def from_json(self, text: str, *, active_task: TaskRecord | None = None) -> MainAgentDecision:
         payload = self._parse_json_object(text)