修复构建失败：替换 FsOp 大写常量为驼峰枚举变体

原因：prost 生成的 FsOp 枚举为驼峰命名（如 FsopGetattr），原代码使用 FSOP_* 常量导致 E0599。

改动：将 src/lib.rs 中所有 FsOp::FSOP_* 替换为 FsOp::Fsop*。

结果：cargo build --release 已通过。

Cargo.lock

@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "addr2line"
@@ -184,6 +184,15 @@ version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3dca9240753cf90908d7e4aac30f630662b02aebaa1b58a3cadabdb23385b58b"
 
+[[package]]
+name = "encoding_rs"
+version = "0.8.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75030f3c4f45dafd7586dd6780965a8c7e8e285a5ecb86713e63a79c5b2766f3"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "env_logger"
 version = "0.8.4"
@@ -472,6 +481,7 @@ checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
 name = "lws_vfs"
 version = "0.1.0"
 dependencies = [
+ "encoding_rs",
  "env_logger",
  "libc",
  "log",