feat: 重构为 Monorepo 架构并实现 HTTP Server

架构变更:
- 采用 pnpm workspaces 实现 Monorepo 结构
- 将现有代码迁移到 packages/core
- 新增 packages/server HTTP 服务层

Server 功能:
- REST API: 会话管理、工具管理、配置管理
- WebSocket: 实时双向通信支持
- SSE: 服务端事件推送
- Hono + Bun 作为运行时

API 端点:
- GET/POST /api/sessions - 会话 CRUD
- GET/POST /api/sessions/:id/messages - 消息管理
- GET /api/sessions/:id/events - SSE 事件流
- WS /api/ws/:sessionId - WebSocket 连接
- GET/POST /api/tools - 工具管理
- GET/PUT /api/config - 配置管理

packages/core/src/agent/index.ts

@@ -0,0 +1,59 @@
+// Types
+export type {
+  AgentMode,
+  PermissionAction,
+  PermissionRule,
+  AgentBashPermission,
+  AgentFilePermission,
+  AgentGitPermission,
+  AgentPermission,
+  AgentModelConfig,
+  AgentToolConfig,
+  AgentInfo,
+  AgentConfigFile,
+  AgentExecutionContext,
+  AgentExecutionResult,
+} from './types.js';
+
+// Registry
+export { AgentRegistry, agentRegistry } from './registry.js';
+
+// Executor
+export { AgentExecutor } from './executor.js';
+
+// Manager
+export {
+  AgentManager,
+  getAgentManager,
+  resetAgentManager,
+  type BackgroundAgent,
+  type BackgroundAgentStatus,
+} from './manager.js';
+
+// Permission Merger
+export {
+  SYSTEM_DEFAULT_PERMISSION,
+  mergePermissions,
+  matchRule,
+  checkBashPermission,
+  checkFilePathPermission,
+} from './permission-merger.js';
+
+// Config Loader
+export {
+  loadAgentConfig,
+  saveAgentConfig,
+  getConfigTemplate,
+} from './config-loader.js';
+
+// Presets
+export {
+  presetAgents,
+  getPresetAgentNames,
+  isPresetAgent,
+  generalAgent,
+  exploreAgent,
+  codeReviewerAgent,
+  buildAgent,
+  planAgent,
+} from './presets/index.js';