updated gitignore and linux appimage script

.gitignore

@@ -4,6 +4,7 @@
 .vscode/
 docs/
 .codex
+build/
 
 # --- Backend (Go) ---
 backend/hightube.db

scripts/package_linux_appimage.sh

@@ -0,0 +1,114 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd -- "${SCRIPT_DIR}/.." && pwd)"
+FRONTEND_DIR="${REPO_ROOT}/frontend"
+DEFAULT_BUNDLE_DIR="${FRONTEND_DIR}/build/linux/x64/release/bundle"
+
+APP_NAME="hightube"
+APP_DISPLAY_NAME="Hightube"
+BUNDLE_DIR="${BUNDLE_DIR:-${DEFAULT_BUNDLE_DIR}}"
+APPDIR="${APPDIR:-${REPO_ROOT}/build/appimage/${APP_NAME}.AppDir}"
+OUTPUT="${OUTPUT:-${REPO_ROOT}/hightube-linux_amd64.AppImage}"
+ICON_SOURCE="${ICON_SOURCE:-${FRONTEND_DIR}/assets/icon/app_icon.png}"
+APPIMAGETOOL="${APPIMAGETOOL:-appimagetool}"
+RUN_FLUTTER_BUILD=0
+
+usage() {
+  cat <<EOF
+Usage: $(basename "$0") [--build]
+
+Package the Flutter Linux release bundle into:
+  ${OUTPUT}
+
+Options:
+  --build   Run "flutter build linux --release" before packaging.
+
+Environment overrides:
+  BUNDLE_DIR     Flutter Linux release bundle directory.
+  OUTPUT         Output AppImage path.
+  APPDIR         Temporary AppDir path.
+  ICON_SOURCE    PNG icon path.
+  APPIMAGETOOL   appimagetool executable path.
+EOF
+}
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --build)
+      RUN_FLUTTER_BUILD=1
+      shift
+      ;;
+    -h|--help)
+      usage
+      exit 0
+      ;;
+    *)
+      echo "Unknown argument: $1" >&2
+      usage >&2
+      exit 2
+      ;;
+  esac
+done
+
+if [[ "${RUN_FLUTTER_BUILD}" -eq 1 ]]; then
+  (cd "${FRONTEND_DIR}" && flutter build linux --release)
+fi
+
+if [[ ! -x "${BUNDLE_DIR}/${APP_NAME}" ]]; then
+  echo "Linux release bundle not found at: ${BUNDLE_DIR}" >&2
+  echo "Run: cd frontend && flutter build linux --release" >&2
+  exit 1
+fi
+
+if [[ ! -f "${ICON_SOURCE}" ]]; then
+  echo "Icon file not found at: ${ICON_SOURCE}" >&2
+  exit 1
+fi
+
+if ! command -v "${APPIMAGETOOL}" >/dev/null 2>&1; then
+  echo "appimagetool not found." >&2
+  echo "Install appimagetool or set APPIMAGETOOL=/path/to/appimagetool" >&2
+  exit 1
+fi
+
+rm -rf "${APPDIR}"
+mkdir -p \
+  "${APPDIR}/usr/bin" \
+  "${APPDIR}/usr/share/applications" \
+  "${APPDIR}/usr/share/icons/hicolor/512x512/apps"
+
+cp -a "${BUNDLE_DIR}/." "${APPDIR}/usr/bin/"
+cp "${ICON_SOURCE}" "${APPDIR}/${APP_NAME}.png"
+cp "${ICON_SOURCE}" "${APPDIR}/usr/share/icons/hicolor/512x512/apps/${APP_NAME}.png"
+
+cat > "${APPDIR}/${APP_NAME}.desktop" <<EOF
+[Desktop Entry]
+Type=Application
+Name=${APP_DISPLAY_NAME}
+Comment=Open source live streaming platform
+Exec=${APP_NAME}
+Icon=${APP_NAME}
+Terminal=false
+Categories=AudioVideo;Player;
+EOF
+
+cp "${APPDIR}/${APP_NAME}.desktop" "${APPDIR}/usr/share/applications/${APP_NAME}.desktop"
+
+cat > "${APPDIR}/AppRun" <<'EOF'
+#!/usr/bin/env bash
+set -euo pipefail
+
+HERE="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+cd "${HERE}/usr/bin"
+exec "./hightube" "$@"
+EOF
+
+chmod +x "${APPDIR}/AppRun" "${APPDIR}/usr/bin/${APP_NAME}"
+rm -f "${OUTPUT}"
+
+APPIMAGE_EXTRACT_AND_RUN=1 ARCH=x86_64 "${APPIMAGETOOL}" "${APPDIR}" "${OUTPUT}"
+chmod +x "${OUTPUT}"
+
+echo "Created AppImage: ${OUTPUT}"