feat: publish Sandwich Hime tooling preview

Publish the exact sanitized Agent Skill and VS Code preview source tree with independent license boundaries, deterministic provenance manifests, and no private development history. Material design and implementation assistance was provided by OpenAI Codex.

Signed-off-by: Cole Speelman <crspeelman@gmail.com>

scripts/test-public-snapshot.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: AGPL-3.0-only
+set -euo pipefail
+root=$(CDPATH= cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)
+[[ -z $(git -C "$root" status --porcelain=v1 --untracked-files=all) ]] || {
+	echo "snapshot test requires a clean committed worktree" >&2
+	exit 1
+}
+parent=$(mktemp -d)
+trap 'rm -rf -- "$parent"' EXIT
+destination=$parent/public
+go run "$root/scripts/export-public-snapshot.go" --source "$root" --destination "$destination"
+test -f "$destination/PUBLIC-SNAPSHOT.json"
+test -f "$destination/PUBLIC-SNAPSHOT.sha256"
+test ! -e "$destination/.git"
+(cd "$destination" && sha256sum -c PUBLIC-SNAPSHOT.sha256)
+if go run "$root/scripts/export-public-snapshot.go" --source "$root" --destination "$destination"; then
+	echo "snapshot exporter altered an existing destination" >&2
+	exit 1
+fi