fix(tests): make the full suite portable across hosts

[oldreceipt]

Windows runs fail on shell-script fixtures, Wine's c: filenames, hardcoded / separators, and CRLF fixtures converted twice. Run executable fixtures through Node, normalize the stock file before building LF and CRLF samples, and compare temporary paths with host path helpers. Child-process arguments, exit codes, cleanup, and byte-for-byte restoration are still checked.

Wine drive-map tests now mock the filesystem entries that Windows cannot create. Bottle discovery still uses real directories. These tests also exposed a hardcoded / in findBottleForPath; it now uses the host path separator.

Verified on Windows:

• Full suite: 182 files passed, 2,705 tests passed, one existing skip, no unhandled errors.
• Typecheck, lint, UI conventions, and i18n checks passed.
• Production build passed with the release backend URL.