♻️ Use rm for the clean target

The node -e rmSync one-liner was carried over from the build-tool
switch and only existed for cross-platform shell safety. The repo is
POSIX-only (sh scripts, Node 26, Linux CI), so rm -rf is simpler and
consistent with the rest of the tooling.

package.json

@@ -43,7 +43,7 @@
         "check:oxfmt": "oxfmt --check ${LEFTHOOK_FILES:-.}",
         "check:oxlint": "oxlint ${LEFTHOOK_FILES:-src}",
         "check:tsc": "tsc",
-        "clean": "node -e \"for (const d of ['dist', 'coverage']) fs.rmSync(d, { recursive: true, force: true })\"",
+        "clean": "rm -rf dist coverage",
         "fix": "npm run fix:oxlint && npm run fix:oxfmt",
         "fix:oxfmt": "oxfmt ${LEFTHOOK_FILES:-.}",
         "fix:oxlint": "oxlint --fix src",