Addresses two Greptile findings on #428.
P1 - buildEnv duplicated PYTHONPATH when the parent environment already
set one. POSIX getenv returns the first match, so the user's stale
PYTHONPATH would shadow the engine's cache dir and break
`from lib import ...` with ModuleNotFoundError. buildEnv now filters
any incoming PYTHONPATH= entry before appending the cache dir. Adds
TestRunDropsPreExistingPythonPath (end-to-end through the stub
interpreter) and TestBuildEnvDropsAllPreExistingPythonPath (direct
unit on the helper) to cover the missed case.
P2 - manifest.compatibility.platforms listed "win32" even though the
release matrix doesn't ship a Windows binary; Claude Desktop would
let Windows users start an install with no matching artifact.
Removed until the Windows packaging follow-up lands. Manifest test
renamed to TestPlatformsMatchShippingMatrix and tightened: now
forbids platforms the release CI doesn't build, with a message
pointing at .github/workflows/release.yml.
go test ./... 38 passed across 4 packages.
Matt Van Horn
61d46b54ee