- Register session.start hook to call prepareXWorkmateArtifacts best-effort
so subsequent export calls have a ready scope.
- Use scope directory birthtime/mtime as a floor for sinceUnixMs when the
scope is already prepared, so files written before export are still
picked up.
- Fall back to scanning params.expectedArtifactDirs (under workspaceRoot)
when no scoped candidates are found, so callers can point at ad-hoc
output directories.
Adds a new gateway method that copies recent outputs from the OpenClaw media
and tmp directories into the current task scope's artifacts directory,
returning a snapshot manifest. XWorkmate Bridge can then call the existing
xworkmate.artifacts.export to hand the snapshot to the XWorkmate APP.
