refactor(beaver): 移除Hermes相关引用和迁移代码，完善Beaver后端主线实现

移除了所有Hermes相关的命名引用，包括：
- 从.gitignore中清理相关构建缓存文件
- 将README中的beaver-home路径配置更新
- 完善backend/README.md文档说明Beaver后端主线实现
- 移除Hermes风格的相关注释和兼容性代码
- 清理nanobot环境变量兼容性处理
- 删除技能迁移和服务迁移相关功能代码
- 更新测试用例中相关命名和函数名

BREAKING CHANGE: 移除了Hermes迁移相关API和CLI命令，不再支持nanobot环境变量兼容性

app-instance/frontend/components/AppRuntimeBridge.tsx

@@ -40,7 +40,7 @@ export function AppRuntimeBridge() {
   const sessionId = useChatStore((state) => state.sessionId);
   const setSessions = useChatStore((state) => state.setSessions);
   const setWsStatus = useChatStore((state) => state.setWsStatus);
-  const setNanobotReady = useChatStore((state) => state.setNanobotReady);
+  const setBeaverReady = useChatStore((state) => state.setBeaverReady);
   const resetProcessState = useChatStore((state) => state.resetProcessState);
   const ingestProcessEvent = useChatStore((state) => state.ingestProcessEvent);
   const statusCheckCleanupRef = React.useRef<(() => void) | null>(null);
@@ -63,14 +63,14 @@ export function AppRuntimeBridge() {
       statusCheckInFlightRef.current = true;
       try {
         await getStatus();
-        setNanobotReady(true);
+        setBeaverReady(true);
       } catch {
-        setNanobotReady(false);
+        setBeaverReady(false);
       } finally {
         statusCheckInFlightRef.current = false;
       }
     });
-  }, [setNanobotReady]);
+  }, [setBeaverReady]);
 
   React.useEffect(() => {
     void loadSessions();
@@ -89,7 +89,7 @@ export function AppRuntimeBridge() {
       } else {
         statusCheckCleanupRef.current?.();
         statusCheckCleanupRef.current = null;
-        setNanobotReady(null);
+        setBeaverReady(null);
       }
     });
 
@@ -98,7 +98,7 @@ export function AppRuntimeBridge() {
       statusCheckCleanupRef.current = null;
       unsubStatus();
     };
-  }, [scheduleStatusCheck, setNanobotReady, setWsStatus]);
+  }, [scheduleStatusCheck, setBeaverReady, setWsStatus]);
 
   React.useEffect(() => {
     const unsubMessage = wsManager.onMessage((data) => {