ToolCallLocation.path and Diff.path emitted over ACP must be absolute
and POSIX-style per the v1 spec (tool-calls.mdx:304-306). The previous
code used platform-specific `node:path` which on Windows prepends the
drive letter (e.g. "D:\...") to POSIX-style inputs like
"/Users/test/project" — silently corrupting paths emitted to ACP
clients on Windows hosts. CI runs on Linux so the latent issue went
undetected. Switch to `node:path/posix` so the path normalisation is
host-OS independent.
Co-Authored-By: Claude <noreply@anthropic.com>