feat: implement core Go application with web server

- Add Go modules with required dependencies (Gin, UUID, JWT, etc.)
- Implement main web server with landing page endpoint
- Add comprehensive API endpoints for health and status
- Include proper error handling and request validation
- Set up CORS middleware and security headers

output/configs/init.sql

@@ -0,0 +1,11 @@
+-- Initialize Dolibarr database for YDN integration
+-- This script creates a separate database for Dolibarr
+
+CREATE DATABASE dolibarr_db WITH ENCODING 'UTF8' LC_COLLATE='C' LC_CTYPE='C';
+
+-- Grant permissions
+GRANT ALL PRIVILEGES ON DATABASE dolibarr_db TO ydn_user;
+
+-- Create extension for UUID generation
+\c dolibarr_db;
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";