refactor: 服务层抽象下沉、异步锁全栈迁移、客户端韧性加固与移动端适配

- 服务层拆分：删除 api/helpers.rs，新增 citation/note/session/pipeline/paper/vision 独立服务模块
  - Agent 工具精简：paper_content+paper_outline 合并为 paper.rs，图片分析逻辑下沉至 services/vision
  - 并发模型升级：std::sync::{Mutex,RwLock} → tokio::sync::{Mutex,RwLock}，消除 async
  上下文中的阻塞风险
  - 客户端加固：HTTP 客户端统一超时配置、ADS 429 / arXiv 503 自动重试、构造函数返回 Result
  - 启动安全：全局 panic hook 日志化、空密码拒绝启动、向量表维度不匹配需显式确认
  - CLI 扩展：构建完整 AppState 复用服务层，新增 Content/Outline/Citations/Search/Process 子命令
  - 前端：移动端汉堡菜单、侧栏滑出面板、引用星系触屏手势（单指拖拽/双指缩放）

Cargo.toml

@@ -21,7 +21,7 @@ path = "src/bin/cli.rs"
 [dependencies]
 tokio = { version = "1", features = ["full"] }
 axum = { version = "0.7", features = ["macros", "multipart"] }
-tower-http = { version = "0.5", features = ["cors", "fs", "trace"] }
+tower-http = { version = "0.5", features = ["cors", "fs", "trace", "set-header"] }
 sqlx = { version = "0.7", features = ["runtime-tokio-rustls", "sqlite", "chrono", "json"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"