feat: add npx support for zero-installation usage (closes #15)

- Add bin configuration to package.json for npx execution
- Implement smart database path resolution for npx/global/local installs
- Create dedicated npm publish script using runtime-only dependencies
- Add .npmignore to control published package contents
- Update README with npx as primary installation method
- Add n8n version badge to README
- Sync version between package.json and package.runtime.json
- Update CHANGELOG for v2.7.8 release

This allows users to run 'npx n8n-mcp' without installing the package,
reducing friction and making it easier to get started with n8n-MCP.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

scripts/publish-npm.sh

@@ -0,0 +1,94 @@
+#!/bin/bash
+# Script to publish n8n-mcp with runtime-only dependencies
+
+set -e
+
+# Color codes for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+echo "🚀 Preparing n8n-mcp for npm publish..."
+
+# Sync version to runtime package first
+echo "🔄 Syncing version to package.runtime.json..."
+npm run sync:runtime-version
+
+# Get version from main package.json
+VERSION=$(node -e "console.log(require('./package.json').version)")
+echo -e "${GREEN}📌 Version: $VERSION${NC}"
+
+# Check if dist directory exists
+if [ ! -d "dist" ]; then
+    echo -e "${RED}❌ Error: dist directory not found. Run 'npm run build' first.${NC}"
+    exit 1
+fi
+
+# Check if database exists
+if [ ! -f "data/nodes.db" ]; then
+    echo -e "${RED}❌ Error: data/nodes.db not found. Run 'npm run rebuild' first.${NC}"
+    exit 1
+fi
+
+# Create a temporary publish directory
+PUBLISH_DIR="npm-publish-temp"
+rm -rf $PUBLISH_DIR
+mkdir -p $PUBLISH_DIR
+
+# Copy necessary files
+echo "📦 Copying files..."
+cp -r dist $PUBLISH_DIR/
+cp -r data $PUBLISH_DIR/
+cp README.md $PUBLISH_DIR/
+cp LICENSE $PUBLISH_DIR/
+cp .env.example $PUBLISH_DIR/
+cp .npmignore $PUBLISH_DIR/ 2>/dev/null || true
+
+# Use runtime package.json (already has correct version from sync)
+echo "📋 Using runtime-only dependencies..."
+cp package.runtime.json $PUBLISH_DIR/package.json
+
+cd $PUBLISH_DIR
+
+# Add required fields from main package.json
+node -e "
+const pkg = require('./package.json');
+pkg.name = 'n8n-mcp';
+pkg.description = 'Integration between n8n workflow automation and Model Context Protocol (MCP)';
+pkg.bin = { 'n8n-mcp': './dist/mcp/index.js' };
+pkg.repository = { type: 'git', url: 'git+https://github.com/czlonkowski/n8n-mcp.git' };
+pkg.keywords = ['n8n', 'mcp', 'model-context-protocol', 'ai', 'workflow', 'automation'];
+pkg.author = 'Romuald Czlonkowski @ www.aiadvisors.pl/en';
+pkg.license = 'MIT';
+pkg.bugs = { url: 'https://github.com/czlonkowski/n8n-mcp/issues' };
+pkg.homepage = 'https://github.com/czlonkowski/n8n-mcp#readme';
+pkg.files = ['dist/**/*', 'data/nodes.db', '.env.example', 'README.md', 'LICENSE'];
+delete pkg.private; // Remove private field so we can publish
+require('fs').writeFileSync('./package.json', JSON.stringify(pkg, null, 2));
+"
+
+echo ""
+echo "📋 Package details:"
+echo -e "${GREEN}Name:${NC} $(node -e "console.log(require('./package.json').name)")"
+echo -e "${GREEN}Version:${NC} $(node -e "console.log(require('./package.json').version)")"
+echo -e "${GREEN}Size:${NC} ~50MB (vs 1GB+ with dev dependencies)"
+echo -e "${GREEN}Runtime deps:${NC} 8 packages"
+
+echo ""
+echo "✅ Ready to publish!"
+echo ""
+echo -e "${YELLOW}⚠️  Important: npm publishing requires OTP authentication${NC}"
+echo ""
+echo "To publish, run:"
+echo -e "  ${GREEN}cd $PUBLISH_DIR${NC}"
+echo -e "  ${GREEN}npm publish --otp=YOUR_OTP_CODE${NC}"
+echo ""
+echo "After publishing, clean up with:"
+echo -e "  ${GREEN}cd ..${NC}"
+echo -e "  ${GREEN}rm -rf $PUBLISH_DIR${NC}"
+echo ""
+echo "📝 Notes:"
+echo "  - Get your OTP from your authenticator app"
+echo "  - The package will be available at https://www.npmjs.com/package/n8n-mcp"
+echo "  - Users can run 'npx n8n-mcp' immediately after publish"