fix: clean global Yarn cache before frontend install

Global /root/.yarn cache contains stale builtin<compat/typescript>
patch references to _tsc.js that don't exist in typescript 7.0.2.
Clean it before each yarn install attempt.

npm_install.py

@@ -2320,6 +2320,13 @@ def _build_frontend(src_frontend: Path, dest_frontend: Path):
 
             shutil.rmtree(src_frontend / ".yarn", ignore_errors=True)
             shutil.rmtree(src_frontend / "node_modules", ignore_errors=True)
+            # Clean global Yarn 4.x cache with stale patch references
+            for g in [Path("/root/.yarn"), Path(os.path.expanduser("~/.config/yarn"))]:
+                if g.exists():
+                    if g.is_dir():
+                        shutil.rmtree(g, ignore_errors=True)
+                    else:
+                        g.unlink(missing_ok=True)
             run(yarn_cmd + ["cache", "clean", "--all"], check=False)
 
             custom_tmp = src_frontend / "tmp-build"