feat: add install.sh for Socket CLI installation

Add installation script that:
- Detects platform and architecture (Linux, Darwin, Windows)
- Downloads appropriate SEA binary from GitHub releases
- Installs to ~/.socket/_dlx/<hash>/ (Socket-managed location)
- Creates symlink in ~/.local/bin for easy access
- Handles macOS quarantine clearing

Binaries installed via this script can self-update using socket self-update.

Author: jdalton

install.sh

@@ -0,0 +1,230 @@
+#!/usr/bin/env bash
+# Socket CLI installation script.
+# Downloads and installs the appropriate Socket CLI binary for your platform.
+
+set -euo pipefail
+
+# Colors for output.
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m' # No Color
+
+# Print colored messages.
+info() {
+  echo -e "${BLUE}ℹ${NC} $1"
+}
+
+success() {
+  echo -e "${GREEN}✓${NC} $1"
+}
+
+error() {
+  echo -e "${RED}✗${NC} $1"
+}
+
+warning() {
+  echo -e "${YELLOW}⚠${NC} $1"
+}
+
+# Detect platform and architecture.
+detect_platform() {
+  local os
+  local arch
+
+  # Detect OS.
+  case "$(uname -s)" in
+    Linux*)
+      os="linux"
+      ;;
+    Darwin*)
+      os="darwin"
+      ;;
+    MINGW*|MSYS*|CYGWIN*)
+      os="win32"
+      ;;
+    *)
+      error "Unsupported operating system: $(uname -s)"
+      exit 1
+      ;;
+  esac
+
+  # Detect architecture.
+  case "$(uname -m)" in
+    x86_64|amd64)
+      arch="x64"
+      ;;
+    aarch64|arm64)
+      arch="arm64"
+      ;;
+    *)
+      error "Unsupported architecture: $(uname -m)"
+      exit 1
+      ;;
+  esac
+
+  echo "${os}-${arch}"
+}
+
+# Get the latest release version from GitHub.
+get_latest_version() {
+  local version
+
+  # Try using curl with GitHub API.
+  if command -v curl &> /dev/null; then
+    version=$(curl -fsSL https://api.github.com/repos/SocketDev/socket-cli/releases/latest | grep -o '"tag_name": *"[^"]*"' | sed 's/"tag_name": *"\([^"]*\)"/\1/')
+  # Fallback to wget.
+  elif command -v wget &> /dev/null; then
+    version=$(wget -qO- https://api.github.com/repos/SocketDev/socket-cli/releases/latest | grep -o '"tag_name": *"[^"]*"' | sed 's/"tag_name": *"\([^"]*\)"/\1/')
+  else
+    error "Neither curl nor wget found. Please install one of them."
+    exit 1
+  fi
+
+  if [ -z "$version" ]; then
+    error "Failed to fetch latest version from GitHub"
+    exit 1
+  fi
+
+  echo "$version"
+}
+
+# Calculate SHA256 hash of a string.
+calculate_hash() {
+  local str="$1"
+
+  if command -v sha256sum &> /dev/null; then
+    echo -n "$str" | sha256sum | cut -d' ' -f1
+  elif command -v shasum &> /dev/null; then
+    echo -n "$str" | shasum -a 256 | cut -d' ' -f1
+  else
+    error "Neither sha256sum nor shasum found"
+    exit 1
+  fi
+}
+
+# Download and install Socket CLI.
+install_socket_cli() {
+  local platform
+  local version
+  local package_name
+  local download_url
+  local dlx_dir
+  local package_hash
+  local install_dir
+  local binary_path
+  local bin_dir
+  local symlink_path
+
+  info "Detecting platform..."
+  platform=$(detect_platform)
+  success "Platform detected: $platform"
+
+  info "Fetching latest version..."
+  version=$(get_latest_version)
+  success "Latest version: $version"
+
+  # Construct package name and download URL.
+  package_name="@socketbin/cli-${platform}"
+  download_url="https://github.com/SocketDev/socket-cli/releases/download/${version}/socketbin-cli-${platform}.tgz"
+
+  info "Downloading Socket CLI from $download_url"
+
+  # Create DLX directory structure.
+  dlx_dir="${HOME}/.socket/_dlx"
+  mkdir -p "$dlx_dir"
+
+  # Calculate content hash for the package.
+  package_hash=$(calculate_hash "${package_name}@${version}")
+  install_dir="${dlx_dir}/${package_hash}"
+
+  # Create installation directory.
+  mkdir -p "$install_dir"
+
+  # Download tarball to temporary location.
+  local temp_tarball="${install_dir}/socket.tgz"
+
+  if command -v curl &> /dev/null; then
+    curl -fsSL -o "$temp_tarball" "$download_url"
+  elif command -v wget &> /dev/null; then
+    wget -qO "$temp_tarball" "$download_url"
+  fi
+
+  success "Downloaded tarball"
+
+  # Extract tarball.
+  info "Extracting binary..."
+  tar -xzf "$temp_tarball" -C "$install_dir"
+
+  # Find the binary (it's in package/bin/socket or package/bin/socket.exe).
+  if [ "$platform" = "win32-x64" ] || [ "$platform" = "win32-arm64" ]; then
+    binary_path="${install_dir}/package/bin/socket.exe"
+  else
+    binary_path="${install_dir}/package/bin/socket"
+  fi
+
+  if [ ! -f "$binary_path" ]; then
+    error "Binary not found at expected path: $binary_path"
+    exit 1
+  fi
+
+  # Make binary executable (Unix-like systems).
+  if [ "$platform" != "win32-x64" ] && [ "$platform" != "win32-arm64" ]; then
+    chmod +x "$binary_path"
+
+    # Clear macOS quarantine attribute.
+    if [ "$platform" = "darwin-x64" ] || [ "$platform" = "darwin-arm64" ]; then
+      xattr -d com.apple.quarantine "$binary_path" 2>/dev/null || true
+    fi
+  fi
+
+  # Clean up tarball.
+  rm "$temp_tarball"
+
+  success "Installed to $binary_path"
+
+  # Create symlink in user's local bin directory.
+  bin_dir="${HOME}/.local/bin"
+  mkdir -p "$bin_dir"
+  symlink_path="${bin_dir}/socket"
+
+  # Remove existing symlink if present.
+  if [ -L "$symlink_path" ] || [ -f "$symlink_path" ]; then
+    rm "$symlink_path"
+  fi
+
+  # Create symlink.
+  ln -s "$binary_path" "$symlink_path"
+  success "Created symlink: $symlink_path -> $binary_path"
+
+  # Check if ~/.local/bin is in PATH.
+  if [[ ":$PATH:" != *":${bin_dir}:"* ]]; then
+    warning "~/.local/bin is not in your PATH"
+    echo ""
+    echo "Add it to your PATH by adding this to your shell profile (~/.bashrc, ~/.zshrc, etc.):"
+    echo ""
+    echo "  export PATH=\"\$HOME/.local/bin:\$PATH\""
+    echo ""
+  else
+    success "~/.local/bin is already in your PATH"
+  fi
+
+  echo ""
+  success "Socket CLI installed successfully!"
+  echo ""
+  info "Run 'socket --help' to get started"
+  info "Run 'socket self-update' to update to the latest version"
+}
+
+# Main execution.
+main() {
+  echo ""
+  echo "Socket CLI Installer"
+  echo "===================="
+  echo ""
+
+  install_socket_cli
+}
+
+main "$@"