fix(cache): restore cached outputs atomically so concurrent cache hits don't fail

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - **Perf** When tasks miss the cache, `vp run` no longer waits for the disk after saving each task's result, so the run finishes sooner. If the computer loses power or the operating system crashes during `vp run`, the cache entries that the run saved can be lost, and those tasks run again next time instead of hitting the cache ([#871](https://github.com/voidzero-dev/vite-task/pull/871)).
 - **Fixed** Running `vp run` in a package that sits inside a workspace folder but isn't listed in its `pnpm-workspace.yaml` `packages` or `package.json` `workspaces` now runs that package's own tasks, instead of treating the enclosing workspace as its root. When both configurations exist, `pnpm-workspace.yaml` takes precedence ([#859](https://github.com/voidzero-dev/vite-task/pull/859)).
+- **Fixed** Tasks that run at the same time and hit the same cache entry no longer intermittently fail with `File exists (os error 17)` while restoring cached outputs ([#846](https://github.com/voidzero-dev/vite-task/issues/846), [#866](https://github.com/voidzero-dev/vite-task/pull/866)).
 - **Fixed** A mistyped or misplaced setting in a task now gets an error that names it. For example, `cache: { outputs: [...] }` now fails with an `unknown field` error that names `outputs` and lists the accepted settings, instead of `data did not match any variant of untagged enum UserTaskDefinition` ([vite-plus#2635](https://github.com/voidzero-dev/vite-plus/issues/2635), [#815](https://github.com/voidzero-dev/vite-task/pull/815)).
 - **Fixed** In cached tasks on Linux and macOS, programs that pass `-1` as a directory descriptor to calls such as `openat` no longer abort. For example, `ps -p <pid>` from procps-ng 4.0.6 or later aborted when the process had already exited ([#862](https://github.com/voidzero-dev/vite-task/pull/862)).
 - **Fixed** `vp run` no longer panics before running a script that contains non-ASCII characters, such as `echo こんにちは`, and no longer cuts off such commands where it displays them ([#861](https://github.com/voidzero-dev/vite-task/pull/861)).

crates/vt/Cargo.toml

@@ -33,6 +33,7 @@ serde_json = { workspace = true }
 supports-color = { workspace = true }
 thiserror = { workspace = true }
 tar = { workspace = true }
+tempfile = { workspace = true }
 tokio = { workspace = true, features = [
   "rt-multi-thread",
   "io-std",
@@ -66,9 +67,6 @@ vt_workspace = { workspace = true }
 wax = { workspace = true }
 zstd = { workspace = true }
 
-[dev-dependencies]
-tempfile = { workspace = true }
-
 [target.'cfg(any(target_os = "windows", target_os = "macos", target_os = "linux"))'.dependencies]
 fspy = { workspace = true }