Add worktree sandbox and test env workflow

scripts/worktree-init.sh

@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+REPO_ROOT=$(cd "${SCRIPT_DIR}/.." && pwd)
+DEFAULT_SANDBOX="${REPO_ROOT}/../galaxyforge-sandbox"
+SANDBOX_PATH="${1:-$DEFAULT_SANDBOX}"
+
+if [[ "$SANDBOX_PATH" != /* ]]; then
+  SANDBOX_PATH="${REPO_ROOT}/${SANDBOX_PATH}"
+fi
+
+SANDBOX_PATH=$(realpath -m "$SANDBOX_PATH")
+
+if ! git -C "$REPO_ROOT" rev-parse --is-inside-work-tree >/dev/null 2>&1; then
+  echo "Fehler: Repo-Root nicht gefunden: $REPO_ROOT" >&2
+  exit 1
+fi
+
+if [[ -e "$SANDBOX_PATH" ]]; then
+  echo "Fehler: Zielpfad existiert bereits: $SANDBOX_PATH" >&2
+  echo "Tipp: Anderen Pfad angeben oder scripts/worktree-destroy.sh verwenden." >&2
+  exit 1
+fi
+
+COMMIT=$(git -C "$REPO_ROOT" rev-parse HEAD)
+
+git -C "$REPO_ROOT" worktree add --detach "$SANDBOX_PATH" "$COMMIT" >/dev/null
+
+echo "Sandbox erstellt (detached HEAD) unter: $SANDBOX_PATH"
+echo "Starten: bash \"$REPO_ROOT/scripts/worktree-up.sh\" \"$SANDBOX_PATH\""