feat: add Node.js prerequisite check and install instructions to README

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

README.md

@@ -16,6 +16,49 @@ Patched AI coding tools for use with custom API endpoints.
 
 ## Quick Start
 
+### Prerequisites Check
+
+Before installing, verify Node.js v24.13+ is installed:
+
+```bash
+# Check Node.js version
+node --version
+
+# If Node.js is missing or version is too old, install:
+# Linux (Debian/Ubuntu):
+sudo apt update && sudo apt install -y nodejs npm
+
+# Linux (RHEL/Fedora):
+sudo dnf install -y nodejs npm
+
+# macOS:
+brew install node
+
+# Windows (PowerShell as Admin):
+winget install OpenJS.NodeJS
+```
+
+### Alternative - Auto-install Node.js
+
+If you need to install or update Node.js automatically:
+
+**Linux:**
+```bash
+curl -fsSL https://deb.nodesource.com/setup_24.x | sudo -E bash - && sudo apt-get install -y nodejs
+```
+
+**macOS:**
+```bash
+/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
+brew install node
+```
+
+**Windows:**
+```powershell
+# As Administrator
+winget install OpenJS.NodeJS
+```
+
 ### Claude Code — Install
 
 Two commands on any platform: