chore(sidecars): allow unused pkg_path under default features

`pkg_path` is consumed only by the cargo + nuget arms, both behind
feature gates. Without those features (the release default) the
parameter is unused. Suppress the warning to keep release builds
warning-free.

Assisted-by: Claude Code:claude-opus-4-7

Author: mikolalysenko

crates/socket-patch-core/src/patch/sidecars/mod.rs

@@ -65,6 +65,7 @@ pub enum SidecarError {
 /// (using the same convention as `apply_package_patch.files_patched`).
 /// `files` is the original patch file map (used to distinguish new
 /// files from modified files via `before_hash.is_empty()`).
+#[allow(unused_variables)] // `pkg_path` is feature-gated below
 pub async fn dispatch_fixup(
     package_key: &str,
     pkg_path: &Path,