Affected: npm: openclaw

## Summary

Remote iMessage attachment fetches used SCP with trust-on-first-use host-key behavior and accepted unvalidated remote host tokens.

Before the fix: - SCP used `StrictHostKeyChecking=accept-new` in the remote attachment path. - `channels.imessage.remoteHost` was not validated as a strict SSH host token.

## Impact

In remote iMessage deployments that use SCP attachment fetching, a first-connection MITM/DNS-poisoning scenario could cause the wrong host key to be trusted. Unsafe remote host token values could also alter SCP argument semantics.

## Affected Packages / Versions

- Package: `openclaw` (npm) - Latest published npm version currently affected: `2026.2.17` - Vulnerable range (structured field): `<= 2026.2.17` - Patched version (pre-set for next release): `>= 2026.2.19`

## Fix

The fix hardens remote attachment SSH/SCP handling by: - requiring `StrictHostKeyChecking=yes` for SCP and SSH tunnel paths, - adding strict `remoteHost` normalization/validation, - adding `--` argument barrier for SCP remote source parsing, - validating `channels.imessage.remoteHost` in config schema, - rejecting unsafe auto-detected host tokens at runtime.

## Fix Commit(s)

- Pushed to `main`: 49d0def6d1e88f002026b1d2a35aa615d48a751a

OpenClaw thanks @allsmog for reporting.