🤖 fix: make node-pty rebuild conditional on Electron presence

When installing mux via npm as a CLI tool, Electron is not present,
causing the postinstall script to fail when trying to rebuild node-pty
for Electron ABI.

This change makes the rebuild conditional:
- If Electron is installed (dev/packaged app): rebuild for Electron ABI
- If Electron is not installed (npm CLI): use Node.js ABI (default)

This allows mux to be installed both as an Electron app (with terminal
support) and as a standalone CLI tool via npm.

_Generated with `mux`_

Author: sreya

package.json

@@ -16,7 +16,7 @@
     "access": "public"
   },
   "scripts": {
-    "postinstall": "npx @electron/rebuild -f -m node_modules/node-pty",
+    "postinstall": "./scripts/postinstall.sh",
     "dev": "make dev",
     "prebuild:main": "./scripts/generate-version.sh",
     "build": "make build",
@@ -171,6 +171,7 @@
     "dist/**/*.json",
     "dist/**/*.png",
     "dist/assets/**/*",
+    "scripts/postinstall.sh",
     "README.md",
     "LICENSE"
   ],

scripts/postinstall.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Only rebuild node-pty for Electron if Electron is installed (for dev or packaged app usage)
+# For npm CLI installs, node-pty will use its default Node.js ABI which works fine
+if [ -d "node_modules/electron" ]; then
+  echo "Electron detected - rebuilding node-pty for Electron ABI..."
+
+  # Use bun x or npx depending on what's available
+  if command -v bun &>/dev/null; then
+    bun x @electron/rebuild -f -m node_modules/node-pty
+  elif command -v npx &>/dev/null; then
+    npx @electron/rebuild -f -m node_modules/node-pty
+  else
+    echo "Warning: Neither bun nor npx found, skipping rebuild"
+    echo "node-pty may not work correctly in Electron"
+  fi
+else
+  echo "Electron not detected - using node-pty with Node.js ABI (CLI mode)"
+fi