The kimi-variant-disambiguation test set only HOME in the spawnSync env,
but os.homedir() on Windows resolves USERPROFILE — so the installer never
found the probe config files and the 'variant mismatch' warning never
fired. Every other installer test in the repo sets both HOME and
USERPROFILE (agent-skills, augment-upgrades, antigravity-upgrades, etc.);
this one was newly written for Phase 5 and missed the pattern.
Also: both new test files carried allow-test-rule exemptions without the
'see #NNN' issue reference required by ADR-456, failing lint-allow-test-rule-refs.
