feat: Acquire a lockfile on distDir in next dev and next build (#84428)

#83961 lets you run both `next dev` and `next build` at the same time, however it's still problematic to run two instances of `next dev` or two instances of `next build` at the same time with the same `distDir`.

This sort of thing can happen to anyone by accident, but we've seen reports of this sort of behavior with AI agents.

#84378 adds a lockfile around just the persistent cache database in Turbopack, which helps, but it's not the only reason this is problematic, so we also need a lock around all of Next.js itself.

I was not able to find a cross-platform lockfile implementation in node that I felt was of sufficient quality, so on POSIX platforms this uses the recently-stabilized Rust stdlib implementation, which appears to be derived from rustc's own lockfile implementation, which has seen widespread use/deployment.

On Windows, since we'd rather have an advisory lock than a mandatory one, this emulates that by instead opening a file with write permissions, and a sharing mode that prohibits shared write access. That means that other processes can safely read the (empty) lockfile without blowing up.

<img width="500" src="https://github.com/user-attachments/assets/1ee4a6c6-2280-4f64-8bf2-ec5369c26db1" />
<img width="500" src="https://github.com/user-attachments/assets/2b04b566-c0b4-42ce-af34-912f3f6afa72" />

Tested on Windows as well:

<img width="1224" height="690" alt="Screenshot 2025-10-07 at 5 44 33 PM" src="https://github.com/user-attachments/assets/e36085b6-9c32-40ac-aca6-4c83e2a53842" />

Author: bgw

Cargo.lock

@@ -123,6 +123,8 @@ turbopack-trace-utils = { workspace = true }
 turbopack-trace-server = { workspace = true }
 turbopack-ecmascript-plugins = { workspace = true, optional = true }
 
+[target.'cfg(windows)'.dependencies]
+windows-sys = "0.60"
 
 # Dependencies for the wasm32 build.
 [target.'cfg(target_arch = "wasm32")'.dependencies]

crates/napi/Cargo.toml

@@ -43,8 +43,10 @@ use swc_core::{
     base::{Compiler, TransformOutput},
     common::{FilePathMapping, SourceMap},
 };
+
 #[cfg(not(target_arch = "wasm32"))]
 pub mod css;
+pub mod lockfile;
 pub mod mdx;
 pub mod minify;
 #[cfg(not(target_arch = "wasm32"))]