chore(tauri): 移除已弃用的 Rust 内嵌后端（消除 52 个编译警告）

- 删除 server/storage/models/events 四模块（axum :10801 后端，功能已全部由 Python 后端 :10085 承担）
- lib.rs：删除 mod 声明，Rust 侧仅保留窗口与生命周期
- Cargo.toml：移除 axum/tower-http/tower/tokio/uuid/chrono/dirs/futures/rust-embed 等 12 个依赖
- cargo check 0 警告，编译更快

src-tauri/Cargo.toml

@@ -17,15 +17,3 @@ tauri = { version = "2", features = ["macos-private-api"] }
 tauri-plugin-opener = "2"
 tauri-plugin-autostart = "2"
 serde = { version = "1", features = ["derive"] }
-serde_json = "1"
-tokio = { version = "1", features = ["full"] }
-axum = { version = "0.8", features = ["macros", "multipart"] }
-tower-http = { version = "0.6", features = ["cors", "fs"] }
-uuid = { version = "1", features = ["v4"] }
-chrono = { version = "0.4", features = ["serde"] }
-tower = "0.5"
-once_cell = "1"
-dirs = "6"
-futures = "0.3"
-tokio-stream = { version = "0.1", features = ["sync"] }
-rust-embed = "8"