Convert to template with dynamic configuration

Add comprehensive environment-based configuration system:
- Created config.js module to centralize all environment variables
- Updated server.js to use config module for all settings
- Added /api/config endpoint to expose company info to frontend
- Created init.js to dynamically inject config into HTML pages
- Updated .env.example with comprehensive configuration options
- Added data attributes to index.html for dynamic content
- Updated Dockerfile to include config.js

This allows users to customize:
- Company name, tagline, and description
- Branding colors (primary, accent, dark)
- Contact information (email, phone, address, hours)
- Social media links
- About page content
- Services offered

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

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

Dockerfile

@@ -10,6 +10,7 @@ RUN npm install --production
 
 # Copy application code
 COPY server.js ./
+COPY config.js ./
 COPY migrations ./migrations
 
 # Copy public directory explicitly