Add install script

Author: MaximoCoder

install.sh

@@ -0,0 +1,82 @@
+#!/bin/sh
+set -e
+
+REPO="MaximoCoder/Enveil"
+BINARY="enveil"
+INSTALL_DIR="/usr/local/bin"
+
+# Detect OS and architecture
+OS=$(uname -s | tr '[:upper:]' '[:lower:]')
+ARCH=$(uname -m)
+
+case "$ARCH" in
+  x86_64)  ARCH="amd64" ;;
+  aarch64) ARCH="arm64" ;;
+  arm64)   ARCH="arm64" ;;
+  *)
+    echo "Unsupported architecture: $ARCH"
+    exit 1
+    ;;
+esac
+
+case "$OS" in
+  linux)  ;;
+  darwin) ;;
+  *)
+    echo "Unsupported OS: $OS"
+    echo "For Windows, use WSL2 and run this installer inside it."
+    exit 1
+    ;;
+esac
+
+ASSET="enveil-${OS}-${ARCH}"
+
+echo "Detecting latest version..."
+VERSION=$(curl -fsSL "https://api.github.com/repos/${REPO}/releases/latest" | grep '"tag_name"' | sed 's/.*"tag_name": "\(.*\)".*/\1/')
+
+if [ -z "$VERSION" ]; then
+  echo "Could not determine latest version"
+  exit 1
+fi
+
+echo "Installing Enveil ${VERSION} for ${OS}/${ARCH}..."
+
+DOWNLOAD_URL="https://github.com/${REPO}/releases/download/${VERSION}/${ASSET}"
+TMP=$(mktemp)
+
+curl -fsSL "$DOWNLOAD_URL" -o "$TMP"
+
+# Verify checksum
+echo "Verifying checksum..."
+CHECKSUMS_URL="https://github.com/${REPO}/releases/download/${VERSION}/checksums.txt"
+EXPECTED=$(curl -fsSL "$CHECKSUMS_URL" | grep "$ASSET" | awk '{print $1}')
+
+if command -v sha256sum > /dev/null 2>&1; then
+  ACTUAL=$(sha256sum "$TMP" | awk '{print $1}')
+elif command -v shasum > /dev/null 2>&1; then
+  ACTUAL=$(shasum -a 256 "$TMP" | awk '{print $1}')
+else
+  echo "Warning: could not verify checksum, sha256sum not found"
+  ACTUAL="$EXPECTED"
+fi
+
+if [ "$EXPECTED" != "$ACTUAL" ]; then
+  echo "Checksum verification failed"
+  echo "Expected: $EXPECTED"
+  echo "Actual:   $ACTUAL"
+  rm -f "$TMP"
+  exit 1
+fi
+
+chmod +x "$TMP"
+sudo mv "$TMP" "${INSTALL_DIR}/${BINARY}"
+
+echo ""
+echo "Enveil ${VERSION} installed successfully"
+echo ""
+echo "To get started:"
+echo "  enveil init"
+echo ""
+echo "To enable shell integration, add this to your ~/.zshrc or ~/.bashrc:"
+echo "  eval \"\$(enveil shell-init)\""
+echo ""