hub v0.38.0: offsite SLICE 2 — capture the box host-key fingerprint

Descriptor.HostFingerprint (SHA256, non-secret), captured at provision via an
x/crypto/ssh keyscan (SSHHostKeyScanner — dials :23, grabs the host key from the
handshake, no ssh binary). Fail-closed: nil scanner or scan failure → error (don't
serve a descriptor the controller can't verify). Pairs with controller v0.106.0
which re-scans + refuses on mismatch (no blind TOFU).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

hub/CHANGELOG.md

@@ -1,5 +1,17 @@
 # Felhom Hub — Changelog
 
+## v0.38.0 — offsite provisioning SLICE 2 (hub side): capture the box host-key fingerprint (2026-07-09)
+
+Pairs with controller v0.106.0. So the controller can VERIFY the box identity instead of blind-TOFU, the hub
+captures the box's SSH host-key fingerprint at provision and serves it in the descriptor.
+
+- `internal/offsite`: `Descriptor.HostFingerprint` (SHA256:…, non-secret). `ProvisionOffsite` now captures it
+  after the resource is ready via a `HostKeyScanner` seam (`SSHHostKeyScanner`, x/crypto/ssh — dials port 23
+  and grabs the host key from the handshake, no ssh binary needed). **Fail-closed:** a nil scanner or a scan
+  failure returns an error (don't serve a descriptor the controller can't verify). The controller re-scans and
+  refuses on mismatch (v0.106.0).
+- Tests: descriptor carries the fingerprint from a faked scanner; a scan failure fails-closed.
+
 ## v0.37.0 — offsite provisioning SLICE 1: Hetzner Cloud-API client + provisioning core (2026-07-09)
 
 Slice 1 of the offsite-provisioning epic. On operator enable, the hub provisions a Hetzner storage-box