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

build_sfx.sh

@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+    echo "Usage: $0 --payload-dir DIR --entrypoint FILE [--output FILE]"
+    echo "       $0 -p DIR -e FILE [-o FILE]"
+    exit 1
+}
+
+# 📥 Default values
+HEADER="sfx_header.sh"
+PAYLOAD_DIR=""
+ENTRYPOINT=""
+OUTPUT="sfx.run"
+
+# 📋 Process arguments
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --payload-dir|-p)
+            PAYLOAD_DIR="$2"
+            shift 2
+            ;;
+        --entrypoint|-e)
+            ENTRYPOINT="$2"
+            shift 2
+            ;;
+        --output|-o)
+            OUTPUT="$2"
+            shift 2
+            ;;
+        *)
+            echo "❌ Unknown option: $1" >&2
+            usage
+            ;;
+    esac
+done
+
+# ✅ Validation
+[[ -z "$PAYLOAD_DIR" || -z "$ENTRYPOINT" ]] && usage
+[[ ! -d "$PAYLOAD_DIR" ]] && { echo "❌ Payload directory not found: $PAYLOAD_DIR" >&2; exit 1; }
+[[ ! -f "$PAYLOAD_DIR/$ENTRYPOINT" ]] && { echo "❌ Entrypoint not found in payload: $ENTRYPOINT" >&2; exit 1; }
+
+# 🧊 Temporary directory
+BUILD_TMP="$(mktemp -d "${TMPDIR:-/tmp}/sfxbuild.XXXXXX")"
+PAYLOAD_ARCHIVE="$BUILD_TMP/payload.tar.zst"
+HEADER_TMP="$BUILD_TMP/sfx_header.final"
+
+cleanup() {
+    rm -rf "$BUILD_TMP"
+}
+trap cleanup EXIT
+
+echo "📦 Creating payload (→ $PAYLOAD_ARCHIVE)..."
+tar -cf - -C "$PAYLOAD_DIR" . | tee >(wc -c > "$BUILD_TMP/raw_size") | zstd -19 -T0 -o "$PAYLOAD_ARCHIVE"
+RAW_SIZE=$(numfmt --to=iec < "$BUILD_TMP/raw_size")
+
+# 🧭 Find marker
+ARCHIVE_LINE=$(grep -n '^__ARCHIVE_BEGIN__$' "$HEADER" | cut -d: -f1)
+[[ ! "$ARCHIVE_LINE" =~ ^[0-9]+$ ]] && {
+    echo "❌ Error: Marker __ARCHIVE_BEGIN__ not found!" >&2
+    exit 1
+}
+echo "🧮 Archive starts from line $ARCHIVE_LINE"
+
+# 🛠️ Replace placeholders
+sed "s|__ARCHIVE_LINE__|$ARCHIVE_LINE|" "$HEADER" | \
+sed "s|__ENTRYPOINT__|$ENTRYPOINT|" | \
+sed '/^__ARCHIVE_BEGIN__$/d' > "$HEADER_TMP"
+
+# 🔗 Combine
+cat "$HEADER_TMP" "$PAYLOAD_ARCHIVE" > "$OUTPUT"
+chmod +x "$OUTPUT"
+
+# 📊 Output
+FINAL_SIZE=$(du -h "$OUTPUT" | cut -f1)
+echo "✅ Done: $OUTPUT"
+echo "   📁 Original size: $RAW_SIZE"
+echo "   📦 Output file: $FINAL_SIZE"

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__