Add install skill for OpenClaw agents (#29)

* feat: add install skill for OpenClaw agents

skill.md provides autonomous install instructions
skill.json provides metadata for programmatic access

* add version check, require user confirm before update

public/skill.json

@@ -0,0 +1,16 @@
+{
+  "name": "crabwalk",
+  "version": "1.0.7",
+  "description": "Real-time companion monitor for OpenClaw agents",
+  "homepage": "https://crabwalk.app",
+  "repository": "https://github.com/luccast/crabwalk",
+  "metadata": {
+    "emoji": "🦀",
+    "category": "monitoring"
+  },
+  "install": {
+    "method": "tarball",
+    "location": "~/.crabwalk",
+    "start_command": "node ~/.crabwalk/.output/server/index.mjs"
+  }
+}

public/skill.md

@@ -0,0 +1,111 @@
+---
+name: crabwalk
+version: 1.0.7
+description: Real-time companion monitor for OpenClaw agents
+homepage: https://crabwalk.app
+repository: https://github.com/luccast/crabwalk
+metadata: {"emoji":"🦀","category":"monitoring"}
+---
+
+# Crabwalk 🦀
+
+Real-time companion monitor for OpenClaw agents. Visualize agent sessions, tool calls, and activity in a reactive graph UI.
+
+## Quick Install
+
+```bash
+# Get latest version
+VERSION=$(curl -s https://api.github.com/repos/luccast/crabwalk/releases/latest | grep '"tag_name"' | cut -d'"' -f4)
+
+# Download and extract
+mkdir -p ~/.crabwalk
+curl -sL "https://github.com/luccast/crabwalk/releases/download/${VERSION}/crabwalk-${VERSION}.tar.gz" | tar -xz -C ~/.crabwalk
+
+# Start server (runs on port 3000)
+node ~/.crabwalk/.output/server/index.mjs
+```
+
+## One-Liner Install
+
+```bash
+VERSION=$(curl -s https://api.github.com/repos/luccast/crabwalk/releases/latest | grep '"tag_name"' | cut -d'"' -f4) && mkdir -p ~/.crabwalk && curl -sL "https://github.com/luccast/crabwalk/releases/download/${VERSION}/crabwalk-${VERSION}.tar.gz" | tar -xz -C ~/.crabwalk && echo "Crabwalk ${VERSION} installed to ~/.crabwalk"
+```
+
+## Running
+
+```bash
+# Default (port 3000)
+node ~/.crabwalk/.output/server/index.mjs
+
+# Custom port
+PORT=8080 node ~/.crabwalk/.output/server/index.mjs
+
+# With gateway auth token
+CLAWDBOT_API_TOKEN=your_token node ~/.crabwalk/.output/server/index.mjs
+```
+
+Open http://localhost:3000 in browser.
+
+## Configuration
+
+| Env Var | Description | Default |
+|---------|-------------|---------|
+| `PORT` | Server port | `3000` |
+| `CLAWDBOT_API_TOKEN` | Gateway auth token | none |
+
+## Features
+
+- `/monitor` — Real-time agent activity graph (ReactFlow)
+- `/workspace` — File browser and markdown viewer
+- Live WebSocket updates from clawdbot gateway
+
+## Requirements
+
+- Node.js 20+
+- clawdbot gateway running on `ws://127.0.0.1:18789`
+
+## Check for Updates
+
+```bash
+INSTALLED=$(cat ~/.crabwalk/package.json 2>/dev/null | grep '"version"' | cut -d'"' -f4)
+LATEST=$(curl -s https://api.github.com/repos/luccast/crabwalk/releases/latest | grep '"tag_name"' | cut -d'"' -f4 | tr -d 'v')
+
+if [ -z "$INSTALLED" ]; then
+  echo "Crabwalk not installed"
+elif [ "$INSTALLED" != "$LATEST" ]; then
+  echo "Update available: $INSTALLED -> $LATEST"
+else
+  echo "Already on latest: $INSTALLED"
+fi
+```
+
+## Updating
+
+**IMPORTANT: Always ask user permission before updating.**
+
+If update available, ask user:
+> "Crabwalk update available (X.X.X -> Y.Y.Y). See release: https://github.com/luccast/crabwalk/releases/tag/vY.Y.Y — Update now?"
+
+Only proceed if user confirms:
+
+```bash
+VERSION=$(curl -s https://api.github.com/repos/luccast/crabwalk/releases/latest | grep '"tag_name"' | cut -d'"' -f4)
+rm -rf ~/.crabwalk
+mkdir -p ~/.crabwalk
+curl -sL "https://github.com/luccast/crabwalk/releases/download/${VERSION}/crabwalk-${VERSION}.tar.gz" | tar -xz -C ~/.crabwalk
+echo "Updated to ${VERSION}"
+```
+
+## Verify Installation
+
+```bash
+# Check version
+cat ~/.crabwalk/package.json | grep '"version"'
+
+# Test server starts
+timeout 5 node ~/.crabwalk/.output/server/index.mjs 2>&1 | head -5 || true
+```
+
+---
+
+Repository: https://github.com/luccast/crabwalk