The parallel runner's isolated-process execution exposed three cli tests
that were passing for the wrong reason on Linux: cbm_zed_config_dir (and
the VS Code/vendor path resolvers) prefer $XDG_CONFIG_HOME over
$HOME/.config, CI runners export it, and an isolated `test-runner cli`
process therefore resolved config paths OUTSIDE the test fixture — the
tests only stayed green in the all-suites single process because an
earlier suite's env mutations leaked into them (hidden cross-suite
coupling, deterministic failure in isolation, macOS unaffected since its
resolvers do not consult XDG).
- cli_detect_agents_finds_zed: save/set XDG_CONFIG_HOME to the fixture's
.config for the detection call, restore after.
- cli_vscode_profile_mcp_uninstall: same pin alongside its existing
HOME/PATH/APPDATA handling.
- cli_durable_profiles_follow_current_vendor_paths: XDG_CONFIG_HOME joins
its unset-and-restore env list.
All 222 cli tests pass locally with a hostile XDG_CONFIG_HOME exported.
No production code changed; no assertion weakened.
Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>