Optimize installer for Ubuntu 24.04 while preserving Termux support; update README for dual-platform usage

[Copilot]

The project was operationally biased toward Termux and lacked a clean Ubuntu 24.04 path. This update makes installation/runtime setup platform-aware and documents Ubuntu-first usage without regressing Termux flows.

• Installer: platform-aware bootstrap (Ubuntu + Termux)

  • Detects environment (TERMUX vs standard Linux) and selects correct package manager path.
  • Uses apt dependency install on Linux (git, golang-go, curl, unzip, jq, ca-certificates) and keeps pkg flow on Termux.
  • Keeps source-based setup flow consistent across platforms (~/Clean-IP-Scanner).

• Xray installation: architecture-correct Linux asset resolution

  • Replaces hardcoded Android-only Xray asset selection with Linux arch mapping:
    • x86_64|amd64 → Xray-linux-64.zip
    • aarch64|arm64 → Xray-linux-arm64-v8a.zip
    • armv7l|armv7 → Xray-linux-arm32-v7a.zip
  • Retains Android ARM64 asset on Termux.
  • Preserves retry/fallback behavior for release download resilience.

• Launcher install behavior on Linux

  • Installs launcher to /usr/local/bin when possible.
  • Falls back to sudo install when direct write is unavailable.
  • Falls back to ~/.local/bin with explicit PATH instruction when no privileged path is available.
  • Keeps $PREFIX/bin install behavior for Termux.

• README: Ubuntu 24.04-first guidance + cross-platform troubleshooting

  • Adds explicit Ubuntu 24.04 install section using install.sh.
  • Updates framing from Termux-only to Ubuntu + Termux support.
  • Adds Ubuntu equivalents in troubleshooting/uninstall sections while retaining Termux commands.

if [[ -n "${TERMUX_VERSION:-}" ]] || [[ "${PREFIX:-}" == *"/com.termux/"* ]]; then
  XRAY_ASSET="Xray-android-arm64-v8a.zip"
else
  case "$(uname -m)" in
    x86_64|amd64) XRAY_ASSET="Xray-linux-64.zip" ;;
    aarch64|arm64) XRAY_ASSET="Xray-linux-arm64-v8a.zip" ;;
    armv7l|armv7) XRAY_ASSET="Xray-linux-arm32-v7a.zip" ;;
  esac
fi