Add uv sync --check flag (#12342)

## Summary

Closes #12338 

## Test Plan

`cargo test`

---------

Co-authored-by: Zanie Blue <contact@zanie.dev>

crates/uv-cli/src/lib.rs

@@ -3285,6 +3285,15 @@ pub struct SyncArgs {
         value_parser = parse_maybe_string,
     )]
     pub python: Option<Maybe<String>>,
+
+    /// Check if the Python environment is synchronized with the project.
+    ///
+    /// If the environment is not up to date, uv will exit with an error.
+    #[arg(long, overrides_with("no_check"))]
+    pub check: bool,
+
+    #[arg(long, overrides_with("check"), hide = true)]
+    pub no_check: bool,
 }
 
 #[derive(Args)]