feat: add root configuration files for mono-repo setup

Add environment template, git ignore rules, and Go workspace
configuration to support mono-repo development workflow.

- .env.example: Environment variables template for all services
- .gitignore: Git ignore rules for Go, Docker, Terraform, Ansible
- go.work: Go workspace file for multi-module support

💘 Generated with Crush

Assisted-by: GLM-4.7 via Crush <crush@charm.land>

.env.example

@@ -0,0 +1,76 @@
+# Environment Variables Template
+# Copy this file to .env and fill in actual values
+
+# Application
+APP_NAME=YDN
+APP_ENV=development
+APP_PORT=8080
+
+# Database (PostgreSQL)
+POSTGRES_HOST=postgres
+POSTGRES_PORT=5432
+POSTGRES_DB=ydn
+POSTGRES_USER=ydn_user
+POSTGRES_PASSWORD=changeme
+
+# Redis
+REDIS_HOST=redis
+REDIS_PORT=6379
+REDIS_PASSWORD=
+
+# Dolibarr (MySQL)
+DOLIBARR_DB_HOST=mysql
+DOLIBARR_DB_PORT=3306
+DOLIBARR_DB=dolibarr
+DOLIBARR_USER=dolibarr_user
+DOLIBARR_PASSWORD=changeme
+DOLIBARR_API_TOKEN=changeme
+
+# Stripe
+STRIPE_PUBLISHABLE_KEY=pk_test_...
+STRIPE_SECRET_KEY=sk_test_...
+STRIPE_WEBHOOK_SECRET=whsec_...
+
+# OVH
+OVH_ENDPOINT=ovh-eu
+OVH_APPLICATION_KEY=changeme
+OVH_APPLICATION_SECRET=changeme
+OVH_CONSUMER_KEY=changeme
+
+# Email (SMTP)
+SMTP_HOST=smtp.mailgun.org
+SMTP_PORT=587
+SMTP_USER=changeme
+SMTP_PASSWORD=changeme
+
+# JWT
+JWT_SECRET=changeme
+JWT_EXPIRATION=24h
+
+# Infrastructure
+TERRAFORM_BACKEND=local
+ANSIBLE_VAULT_PASSWORD=changeme
+
+# Grav CMS
+GRAV_ADMIN_USER=admin
+GRAV_ADMIN_PASSWORD=changeme
+GRAV_ADMIN_EMAIL=admin@example.com
+
+# Terraform Providers
+TERRAFORM_PROVIDER_LOCAL=libvirt
+TERRAFORM_PROVIDER_PROD=ovh
+
+# Libvirt (Local Testing)
+LIBVIRT_URI=qemu:///system
+
+# OVH (Production)
+OVH_PROJECT_ID=changeme
+OVH_SSH_KEY_NAME=ydn-deploy
+
+# Monitoring
+ENABLE_METRICS=true
+METRICS_PORT=9090
+
+# Logging
+LOG_LEVEL=info
+LOG_FORMAT=json