feat: add universal install script for macOS & Linux

- Add install.sh with curl one-liner installation
- Supports macOS (Homebrew), Debian/Ubuntu (apt), Fedora (dnf), Arch (pacman), Alpine (apk)
- Auto-detects OS, architecture, and Linux distro
- Checks/installs Node.js 18+, GNU Screen, warns about Claude CLI
- Clones to ~/.claudeman/app, builds, adds to PATH
- Optional systemd service setup on Linux
- Add postinstall.js for npm install verification
- Update README with simplified installation section

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -201,45 +201,34 @@ Run **20 parallel sessions** with full visibility:
 
 ---
 
-## Quick Start
+## Installation
+
+### macOS & Linux
 
 ```bash
-# Clone and build
-git clone https://github.com/Ark0N/claudeman.git
-cd claudeman
-npm install && npm run build
+curl -fsSL https://raw.githubusercontent.com/Ark0N/claudeman/master/install.sh | bash
+```
 
-# Start the web interface
-claudeman web
+### npm (alternative)
 
-# Open http://localhost:3000
+```bash
+npm install -g claudeman
+```
+
+### Requirements
+
+- Node.js 18+
+- [Claude CLI](https://docs.anthropic.com/en/docs/claude-code/getting-started) installed
+- GNU Screen (`apt install screen` / `brew install screen`)
+
+## Getting Started
+
+```bash
+claudeman web --https
+# Open https://localhost:3000
 # Press Ctrl+Enter to start your first session
 ```
 
-### More Options
-
-```bash
-# Custom port
-claudeman web -p 8080
-
-# Development mode (no build needed)
-npx tsx src/index.ts web
-
-# HTTPS (required for browser notifications)
-claudeman web --https
-
-# Run as systemd service (auto-restarts, survives logout)
-ln -sf $(pwd)/scripts/claudeman-web.service ~/.config/systemd/user/
-systemctl --user daemon-reload
-systemctl --user enable --now claudeman-web
-loginctl enable-linger $USER
-```
-
-**Requirements:**
-- Node.js 18+
-- Claude CLI installed (PATH is auto-resolved from common locations like `~/.local/bin`)
-- GNU Screen (`apt install screen` / `brew install screen`)
-
 ---
 
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