Parse `dist-workspace.toml` for version (#17868)

Extends https://github.com/astral-sh/ruff/pull/17866, using
`dist-workspace.toml` as a source of truth for versions to enable
version retrieval in distributions that are not Git repositories (i.e.,
Python source distributions and source tarballs consumed by Linux
distros).

I retain the Git tag lookup from
https://github.com/astral-sh/ruff/pull/17866 as a fallback — it seems
harmless, but we could drop it to simplify things here.

I confirmed this works from the repository as well as Python source and
binary distributions:

```
❯ uv run --refresh-package ty --reinstall-package ty -q --  ty version
ty 0.0.1-alpha.1+5 (2eadc9e61 2025-05-05)
❯ uv build
...
❯ uvx --from ty@dist/ty-0.0.0a1.tar.gz --no-cache -q -- ty version
ty 0.0.1-alpha.1
❯ uvx --from ty@dist/ty-0.0.0a1-py3-none-macosx_11_0_arm64.whl -q -- ty version
ty 0.0.1-alpha.1
```

Requires https://github.com/astral-sh/ty/pull/36

cc @Gankra and @MichaReiser for review.

crates/ty/build.rs

@@ -12,12 +12,39 @@ fn main() {
         .join("..")
         .join("..");
 
+    version_info(&workspace_root);
     commit_info(&workspace_root);
 
     let target = std::env::var("TARGET").unwrap();
     println!("cargo::rustc-env=RUST_HOST_TARGET={target}");
 }
 
+/// Retrieve the version from the `dist-workspace.toml` file and set `TY_VERSION`.
+fn version_info(workspace_root: &Path) {
+    let dist_file = workspace_root.join("dist-workspace.toml");
+    if !dist_file.exists() {
+        return;
+    }
+
+    println!("cargo:rerun-if-changed={}", dist_file.display());
+
+    let dist_file = fs::read_to_string(dist_file);
+    if let Ok(dist_file) = dist_file {
+        let lines = dist_file.lines();
+        for line in lines {
+            if line.starts_with("version =") {
+                let (_key, version) = line.split_once('=').unwrap();
+                println!(
+                    "cargo::rustc-env=TY_VERSION={}",
+                    version.trim().trim_matches('"')
+                );
+                break;
+            }
+        }
+    }
+}
+
+/// Retrieve commit information from the Git repository.
 fn commit_info(workspace_root: &Path) {
     // If not in a git repository, do not attempt to retrieve commit information
     let git_dir = workspace_root.join(".git");

crates/ty/src/version.rs

@@ -54,7 +54,10 @@ pub(crate) fn version() -> VersionInfo {
         last_tag: option_env_str!("TY_LAST_TAG"),
     });
 
-    let version = commit_info
+    // The version is pulled from `dist-workspace.toml` and set by `build.rs`
+    let version = option_env_str!("TY_VERSION").unwrap_or_else(|| {
+        // If missing, using the last tag
+        commit_info
             .as_ref()
             .and_then(|info| {
                 info.last_tag.as_ref().map(|tag| {
@@ -63,7 +66,8 @@ pub(crate) fn version() -> VersionInfo {
                         .unwrap_or(tag.clone())
                 })
             })
-        .unwrap_or("unknown".to_string());
+            .unwrap_or("unknown".to_string())
+    });
 
     VersionInfo {
         version,