feat: add script for creating self-extracting archives

- Introduces a script to build self-extracting archives with validation
- Includes payload compression, placeholder replacement, and output creation
- Adds a header script to extract and execute the embedded entrypoint

sfx_header.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+TMPDIR="$(mktemp -d "${TMPDIR:-/tmp}/sfx.XXXXXX")"
+ARCHIVE_LINE=__ARCHIVE_LINE__
+
+cleanup() {
+    rm -rf "$TMPDIR"
+}
+trap cleanup EXIT
+
+tail -n +$ARCHIVE_LINE "$0" | unzstd | tar -xf - -C "$TMPDIR"
+
+ENTRYPOINT="$TMPDIR/__ENTRYPOINT__"
+chmod +x "$ENTRYPOINT"
+"$ENTRYPOINT" "$@"
+exit_code=$?
+exit $exit_code
+__ARCHIVE_BEGIN__