Refactor lib/conductor-env-shim.ts to export promoteConductorEnv()
so unit tests can manipulate env and call it directly (a bare side-
effect IIFE on import isn't reachable from bun:test once cached).
The on-import IIFE still runs — existing four-entry-point imports
keep working unchanged.
test/conductor-env-shim.test.ts covers all three branches:
GSTACK_FOO present + FOO empty → promotion; FOO already set →
no-overwrite; nothing in env → no-op.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Garry Tan