install.ps1 already kept uv's bootstrap Python out of the Windows
registry, but setup-hermes.ps1 did not, so every Windows dev checkout
registered that interpreter under HKCU. The flag is Windows-only; the
POSIX installers take it too so every bootstrap issues the same command.
Root-level tests/ is for root-level modules; 19 files testing scripts/, 3 testing
pm/ and 5 testing hermes_cli/ move to the mirrored directory (workflow file lists
and cross-imports updated; path arithmetic bumped one level).
tests/pm gains a conftest with the isolated_machine_home fixture that seven
modules had copy-pasted verbatim.