feat(context): 添加上下文压缩 API 和 UI 组件

Server API:
- 扩展 Agent Adapter 接口添加压缩相关方法
- 新增 context.ts 路由 (GET /sessions/:id/context, POST /sessions/:id/compress)
- 扩展 config.ts 添加摘要模型配置接口 (GET/PUT /config/summary)

UI 组件:
- 新增 ContextUsage 组件显示上下文使用情况
- 扩展 ConfigPanel 添加摘要模型配置区域
- 添加 API 客户端方法和类型定义

Web 集成:
- 在 Chat 页面头部集成 ContextUsage 紧凑模式显示

packages/core/src/index.ts

@@ -1,7 +1,19 @@
 export { Agent } from './core/agent.js';
 export { toolRegistry, todoManager, initTaskContext, updateTaskDescription, updateSkillDescription } from './tools/index.js';
-export { loadConfig, saveConfig, getConfig, loadVisionConfig } from './utils/config.js';
-export type { VisionConfig } from './utils/config.js';
+export { loadConfig, saveConfig, getConfig, loadVisionConfig, loadSummaryConfig } from './utils/config.js';
+export type { VisionConfig, SummaryConfig } from './utils/config.js';
+
+// Context compression
+export {
+  CompressionManager,
+  CompressionStatus,
+  DEFAULT_COMPRESSION_CONFIG,
+} from './context/index.js';
+export type {
+  TokenUsage,
+  CompressionConfig,
+  DetailedCompressionResult,
+} from './context/index.js';
 export { SessionStorage } from './session/storage.js';
 export { SessionManager } from './session/index.js';
 export type { SessionData, SessionSummary } from './session/types.js';