module: cache nearest parent package.json per directory - #65326

Cold require() of a 1000-module CommonJS tree gets ~6 % faster (100 runs, ***) and module/module-require.js type='.js'
+13.7 %, by looking up the nearest parent package.json once per directory instead of once per file.

module/module-require.js n=10000 type='.js'                                     ***    13.69 %  ±2.36%
module/module-require.js n=10000 type='.json' | 'dir' (don't use this path)              -2.1 %  (relink noise is ±1 %)
cold require() of a generated 1000-module tree, flat layout          (100 runs) ***     6.37 %  ±1.76%
  same, pnpm-style symlinked node_modules                                       ***     6.56 %  ±0.90%
  same, with NODE_COMPILE_CACHE warm                                            ***     5.10 %  ±1.43%

getNearestParentPackageJSON(checkPath) - called for every CommonJS module to find "type", and by findPackageJSON -
memoized per file, so N modules in a directory meant N calls into the native package.json reader. The result only depends
on the directory the traversal starts from, so the JS-side cache is now keyed by that directory, derived with the same rule
the native side uses (trailing separator → that directory, else dirname). With the permission model enabled the per-path
behavior is kept, because the native call performs a per-path read check. Same return values, same objects, same lifetime
(both caches were already permanent). 1000 native calls → 236 for the tree above.

Tests: behavior is unchanged; test-module-*, test-require-*, test-esm-*, es-module and test-permission-*
(which exercises the per-path branch) pass. Happy to add a call-count test if wanted.

Disclosure: the code, test, measurements and this description were written by Claude Code, directed and reviewed by @codebytere.