fix: remove stale patch-package postinstall

[999axel999]

Summary

• Remove the stale patch-package/grunt-mocha-cli postinstall hook and its unused devDependency.
• Keep a no-op scripts/postinstall.js with a #939 TODO documenting the follow-up Windows-shell investigation instead of silently deleting the context.
• Bump the bundled EO parser version from 0.61.0 to 0.61.1, which fixes the parser-side failure that made the earlier cleanup look suspicious.
• Add a regression test proving the stale install hook and lockfile metadata are gone.

Closes #939

Tests

• node parser smoke check for slash syntax against EO 0.61.1
• .\node_modules\.bin\mocha.cmd test/test_postinstall.js --timeout 1200000
• npm.cmd exec -- eslint test/test_postinstall.js scripts/postinstall.js
• git diff --check
• GitHub Actions for 7f3e79777a4f61ad85e5a1901cac42bd93bca6b1: pdd, markdown-lint, copyrights, yamllint, shellcheck, typos, actionlint, eslint, reuse, xcop, itest, and grunt all passed.

Prepared with local automation assistance and reviewed before submission.

[yegor256]

@999axel999 please, fix merge conflicts

[yegor256]

@999axel999 this change looks weird: you don't change anything, just deleting what works. Apparently, CI is clean after your changes, but this most probably means that CI is weak.

[999axel999]

@yegor256 I reworked the PR after your feedback. It no longer relies on a blind deletion: the branch now bumps the EO parser from 0.61.0 to 0.61.1, keeps a no-op scripts/postinstall.js with a #939 follow-up TODO explaining the Windows-shell patch question, and adds a regression test that verifies the stale patch-package hook and lockfile metadata are gone. The current head 7f3e797 is green in GitHub Actions, including itest and grunt.