fix: run the auto-install postinstall on Windows too

[plum117]

Why

npm runs install scripts with cmd.exe on Windows, and cmd.exe has no test command. The postinstall script started with test -f ./dist/install.js, so on a typical Windows machine it always printed "Skipping install, project not built!", and EDGEDRIVER_AUTO_INSTALL / GECKODRIVER_AUTO_INSTALL did nothing.

The GitHub Windows runner has Git's Unix tools (test.exe) on PATH, so CI did not show it: the first test commit passed on Windows. With PATH limited to Node.js and System32, as on a user's machine, the test fails on Windows on the old script (run: runs dist/install.js when it is built, on every OS failed in both packages).

Change

• postinstall: a node -e check replaces test -f. It works in sh and cmd.exe. As before, it prints "Skipping install, project not built!" when dist is missing (the workspace install), and a failed download still does not fail the install.
• READMEs: pnpm 10+ and Bun run install scripts only for approved packages (pnpm approve-builds, trustedDependencies), and npm 11 warns until npm install-scripts approve <package>. If the download fails, the driver downloads on first use.
• Upgrade note: on Windows, the auto-install flags now download the driver during the install.

Test plan

• New tests/postinstall.test.ts in edgedriver and geckodriver: run the real script with npm's default shell and a minimal PATH. Red on Windows CI with the old script, green on macOS
• EDGEDRIVER_AUTO_INSTALL=1 npm i <packed tarball> (npm 11.19): the driver downloads during the install
• Windows CI green with the fix

🤖 Generated with Claude Code

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no actionable issues were found.

Summary

Makes edgedriver and geckodriver installation scripts work on Windows without Unix tools.

• Edgedriver and geckodriver can install their drivers on Windows.

_{Reviews (1) · Last reviewed commit: "fix: run the auto-install postinstall on..." · Reviewed by Greptile}