The backup temp manifest is created via os.tmpdir() and passed to tar.c
alongside the included asset paths. When TMPDIR resolves inside a backed-up
asset (for example a sandboxed cron run with TMPDIR=~/.openclaw/tmp), the
recursive walk of that asset visits the same manifest a second time and both
copies are remapped to <archiveRoot>/manifest.json. backup-verify then fails
with 'Expected exactly one backup manifest entry, found 2'.
Add chooseBackupTempRoot() that prefers os.tmpdir() and falls back to the
output directory (already validated as outside every asset and writable by
the caller) when the system tempdir overlaps a source path. A defensive
guard re-checks the fallback. A tar filter alone cannot fix this because
the filter fires for both the explicit-arg and the traversed entry, so
excluding by path drops the manifest entirely.
Add regression tests for tmpdir nested in the state dir and tmpdir equal
to the state dir.
00ec151f68