fix(cache): fingerprint only whether files in node_modules/.bin exist

[wan9chi]

Motivation

pnpm's shims in node_modules/.bin embed the absolute workspace path, in NODE_PATH and in a trailing # cmd-shim-target= comment. Almost every task runs a dependency's executable through one, so installing with the workspace at another path, such as another clone or a CI checkout, made those tasks miss with 'node_modules/.bin/tsc' modified.

Changes

• Files directly inside a node_modules/.bin directory are now fingerprinted only by whether they exist. A missing shim still differs from an existing one.
• What a shim runs is still tracked through the package files the task reads. The shim's exec target is a relative path, and only pnpm reads cmd-shim-target.
• This doesn't need the workspace root or the Windows path variants (C:\ws, C:/ws, /mnt/c/ws) that rewriting the absolute paths in place would. It also covers .cmd and .ps1 shims, pnpm's global virtual store, and npm/Yarn symlinks.
• Trade-off: with pnpm's global virtual store, the dependency version in NODE_PATH was an incidental signal that a dependency changed, since reads in the store are outside the workspace and untracked. Tracking store reads properly is a separate problem.

🤖 Generated with Claude Code

[github-actions]

fspy benchmark

linux

dynamic/launch             change  +4.75%  [-14.77% .. +24.37%]  overhead   +62.75%
dynamic/access             change  +0.26%  [ -5.47% .. +13.49%]  overhead    +8.46%
dynamic/access-relative    change  +0.44%  [-10.78% ..  +8.74%]  overhead   +45.26%
dynamic/access-contended   change  +3.07%  [ -3.41% ..  +8.35%]  overhead    +9.30%
static/launch              change  +1.95%  [-22.13% .. +37.09%]  overhead  +155.48%
static/access              change  +4.82%  [-17.50% .. +55.47%]  overhead +1489.50%
static/access-relative     change  +0.32%  [-21.54% .. +26.43%]  overhead +1473.56%
static/access-contended    change  +4.35%  [ -7.84% .. +18.26%]  overhead +3567.39%

macos

dynamic/launch             change  -0.72%  [ -3.75% ..  +2.71%]  overhead  +216.72%
dynamic/access             change  -0.36%  [ -2.27% ..  +1.95%]  overhead    +2.98%
dynamic/access-relative    change  +0.28%  [ -2.81% ..  +3.65%]  overhead  +265.78%
dynamic/access-contended   change  +0.37%  [ -3.55% ..  +3.29%]  overhead    +3.94%

windows

dynamic/launch             change  +0.27%  [ -6.19% ..  +5.06%]  overhead   +25.85%
dynamic/access             change  +0.00%  [ -9.56% ..  +4.68%]  overhead    +0.90%
dynamic/access-relative    change  +0.35%  [ -2.07% .. +20.57%]  overhead    +1.60%
dynamic/access-contended   change  +1.37%  [ -3.89% .. +23.31%]  overhead    +4.68%