port pi-devbox v1.1.4–v1.1.6 hardening; bump opencode 1.17.7→1.17.8

Functional (not verbatim) port of the build-provenance, CI-hardening, SSH
and shell fixes from the sibling pi-devbox repo, adapted to opencode-devbox's
companions and two-variant (base/omos) shape. Defaults unchanged → canonical
CI build stays byte-identical apart from the opencode bump and the
(cache-free) provenance layer.

Fixed:
- SSH read-only ~/.ssh ControlPath: setup-lan-access.sh now renders the
  writable ~/.ssh-local/config sidecar (ControlPath redirect + Include) on
  EVERY host OS instead of exit 0-ing on native Linux; jump-specific blocks
  gated behind new NEED_JUMP flag. dssh/dscp + ControlMaster now survive a
  read-only ~/.ssh on native-Linux hosts. (pi-devbox v1.1.5)
- bash history loss in nested/tmux shells: DEVBOX_HIST_SET no longer exported
  so each shell re-installs its own history -a flush. (pi-devbox v1.1.4)

Added:
- build provenance: OCI labels + /etc/opencode-devbox/build-manifest.json
  written from ground truth (opencode --version, installed omos version,
  /opt/mempalace-toolkit HEAD); wired into build-variant-* and smoke-* jobs;
  smoke-test.sh asserts manifest + label. (pi-devbox v1.1.6)
- scripts/check-base-hash.sh CI guard: fails if a Dockerfile.base ARG *_REF
  is not folded into the base_tag hash. (pi-devbox v1.1.6)
- overridable MEMPALACE_TOOLKIT_REPO build-arg in Dockerfile.base. (v1.1.6)

Changed:
- resolve-versions: fail-loud validation (SHA / semver) that aborts the
  release instead of silently falling back to floating main; adds shell: bash
  (set -o pipefail is illegal under the runner default dash). (pi-devbox v1.1.6)

Bumped:
- opencode-ai 1.17.7 → 1.17.8 (current npm latest stable).

Deferred (needs a decision): opencode.json merge-on-recreate — see CHANGELOG.

rootfs/home/developer/.bash_aliases

@@ -89,9 +89,16 @@ fi
 # we append with a newline separator to avoid the ';;' parse error
 # described at the top of this file. Guarded so repeated sourcing
 # (e.g. `exec bash`) doesn't stack duplicates.
+#
+# The guard MUST stay shell-local (NOT exported): if it leaks into child
+# processes, every nested shell -- crucially each tmux pane, which inherits
+# the tmux server's env -- skips installing `history -a` and only persists
+# history on a clean exit. Abrupt termination (docker stop, tmux kill-server,
+# SIGKILL) then loses that shell's in-memory history. Keeping it unexported
+# means each new interactive shell re-installs its own per-prompt flush.
 if [ -z "${DEVBOX_HIST_SET:-}" ]; then
   PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND$'\n'}history -a"
-  export DEVBOX_HIST_SET=1
+  DEVBOX_HIST_SET=1
 fi
 
 # ── Prompt: show [opencode-devbox] tag so it's obvious you're in the container