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/nginx.conf

@@ -0,0 +1,156 @@
+events {
+    worker_connections 1024;
+}
+
+http {
+    include       /etc/nginx/mime.types;
+    default_type  application/octet-stream;
+
+    # Logging
+    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
+                   '$status $body_bytes_sent "$http_referer" '
+                   '"$http_user_agent" "$http_x_forwarded_for"';
+
+    access_log /var/log/nginx/access.log main;
+    error_log /var/log/nginx/error.log warn;
+
+    # Performance
+    sendfile on;
+    tcp_nopush on;
+    tcp_nodelay on;
+    keepalive_timeout 65;
+    types_hash_max_size 2048;
+    client_max_body_size 10M;
+
+    # Gzip compression
+    gzip on;
+    gzip_vary on;
+    gzip_min_length 1024;
+    gzip_proxied any;
+    gzip_comp_level 6;
+    gzip_types
+        text/plain
+        text/css
+        text/xml
+        text/javascript
+        application/json
+        application/javascript
+        application/xml+rss
+        application/atom+xml
+        image/svg+xml;
+
+    # Rate limiting
+    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
+    limit_req_zone $binary_remote_addr zone=login:10m rate=1r/s;
+
+    # Upstream servers
+    upstream ydn_app {
+        server ydn-app:8080;
+    }
+
+    upstream dolibarr {
+        server ydn-dolibarr:80;
+    }
+
+    # Security headers
+    add_header X-Frame-Options DENY always;
+    add_header X-Content-Type-Options nosniff always;
+    add_header X-XSS-Protection "1; mode=block" always;
+    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+    add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; font-src 'self' data:; connect-src 'self' https://api.stripe.com https://js.stripe.com; frame-src https://js.stripe.com https://hooks.stripe.com;" always;
+
+    server {
+        listen 80;
+        server_name localhost;
+
+        # Redirect HTTP to HTTPS in production
+        # return 301 https://$server_name$request_uri;
+
+        # Security
+        server_tokens off;
+
+        # Main application
+        location / {
+            proxy_pass http://ydn_app;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+            
+            # Timeouts
+            proxy_connect_timeout 30s;
+            proxy_send_timeout 30s;
+            proxy_read_timeout 30s;
+        }
+
+        # API with rate limiting
+        location /api/ {
+            limit_req zone=api burst=20 nodelay;
+            
+            proxy_pass http://ydn_app;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+        }
+
+        # Login endpoint with stricter rate limiting
+        location /api/v1/login {
+            limit_req zone=login burst=5 nodelay;
+            
+            proxy_pass http://ydn_app;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+        }
+
+        # Static files
+        location /static/ {
+            alias /usr/share/nginx/html/static/;
+            expires 1y;
+            add_header Cache-Control "public, immutable";
+            add_header X-Content-Type-Options nosniff;
+        }
+
+        # Stripe webhooks
+        location /api/v1/webhooks/stripe {
+            proxy_pass http://ydn_app;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+            
+            # Allow larger payloads for webhooks
+            client_max_body_size 1M;
+        }
+
+        # Dolibarr
+        location /dolibarr/ {
+            proxy_pass http://dolibarr/;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+            
+            # PHP specific settings
+            proxy_buffers 8 16k;
+            proxy_buffer_size 32k;
+        }
+
+        # Health check
+        location /health {
+            proxy_pass http://ydn_app;
+            access_log off;
+        }
+
+        # Deny access to sensitive files
+        location ~ /\. {
+            deny all;
+        }
+
+        location ~ \.(conf|log|sql|env)$ {
+            deny all;
+        }
+    }
+}