[SaladDay]

Problem

The Core image carries only native-installers/catalog.json. Without a release base URL the catalog has no download URLs, so Core requires the archives at /opt/oac/native-installers/<platform>.tar.gz. The offline archive ships them, but install.py never installed them:

• A checkout distribution built with OAC_NATIVE_INSTALLER_BUILD_DIR (Develop → Install a checkout without publishing a release) left Core in a restart loop: open /opt/oac/native-installers/linux-amd64.tar.gz: no such file or directory.
• An offline release installation carried ~865 MiB of native installers that nothing served; self-hosted machines were redirected to GitHub instead.

Change

• install.py copies the bundle's native-installers/ into <installation>/native-installers/<commit>, makes it readable by Core, binds it read-only at /opt/oac/native-installers, and removes other releases' copies after a successful start.
• oac upgrade drops that bind and directory together with the existing /node-payload bind when an offline installation moves to a published release.
• Maintainer guide (EN/zh) states where the offline copies go.

Validation

• python3 -m unittest deploy/test_install_source.py (13 tests, new: install + upgrade prune)
• go test ./services/core/cmd/oac/ and go vet
• Live: a 13cbbf8 offline bundle with the native catalog on the mx test host. Before the change Core restarted in a loop; after rerunning the patched install.py, Core is healthy with the archives bound.

---

^{Need help on this PR? Tag @codesmith-bot with what you need.}