The reprovision retired gitea.westgate.pw in favour of git.westgate.pw, but
internal/topdata still defaulted to the old host and made a live API call
during the native buildability check, so once CI checkout was fixed the
parts tests failed (DNS, then HTTP 404).
- defaultGiteaBaseURL -> https://git.westgate.pw; normalize git-ssh. -> git.
- Add stubEmptyPartsManifest (stub_test.go) and call it from the 2 non-optional
parts tests so they exercise the build offline. Per-test (t.Setenv) on
purpose: a global TestMain SOW_ASSETS_SERVER_URL would override the
git-remote-derived server other tests configure. VFX tests already pass
(optional consumer ignores HTTP 404).
make check + make smoke green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
