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/lib/store.ts

@@ -14,7 +14,7 @@ import type {
 } from '@/types';
 import type { WsStatus } from '@/lib/api';
 
-const ACTIVE_SESSION_STORAGE_KEY = 'nanobot_active_session_id';
+const ACTIVE_SESSION_STORAGE_KEY = 'beaver_active_session_id';
 
 function getInitialSessionId(): string {
   if (typeof window === 'undefined') {
@@ -40,7 +40,7 @@ interface ChatStore {
   streamingContent: string;
   wsStatus: WsStatus;
   isThinking: boolean;
-  nanobotReady: boolean | null;
+  beaverReady: boolean | null;
   sessions: Session[];
   processRuns: ProcessRun[];
   processEvents: ProcessEvent[];
@@ -68,7 +68,7 @@ interface ChatStore {
   clearMessages: () => void;
   setWsStatus: (status: WsStatus) => void;
   setIsThinking: (thinking: boolean) => void;
-  setNanobotReady: (ready: boolean | null) => void;
+  setBeaverReady: (ready: boolean | null) => void;
   resetProcessState: () => void;
   ingestProcessEvent: (event: ProcessWsEvent) => void;
   setSessionProcess: (sessionId: string, projection: SessionProcessProjection) => void;
@@ -135,7 +135,7 @@ export const useChatStore = create<ChatStore>((set) => ({
   streamingContent: '',
   wsStatus: 'disconnected',
   isThinking: false,
-  nanobotReady: null,
+  beaverReady: null,
   sessions: [],
   processRuns: [],
   processEvents: [],
@@ -175,7 +175,7 @@ export const useChatStore = create<ChatStore>((set) => ({
   clearMessages: () => set({ messages: [], streamingContent: '' }),
   setWsStatus: (status) => set({ wsStatus: status }),
   setIsThinking: (thinking) => set({ isThinking: thinking }),
-  setNanobotReady: (ready) => set({ nanobotReady: ready }),
+  setBeaverReady: (ready) => set({ beaverReady: ready }),
   resetProcessState: () =>
     set({
       processRuns: [],