✨ feat(infrastructure): introduce ansible deployment for taler services

- add ansible playbooks and roles for deploying taler exchange and merchant
- configure PostgreSQL, GNU Taler repositories, and services

🔧 chore(config): provide example env and gitignore for sensitive files

- create .env-example with placeholders for sensitive info
- add .gitignore entries for .env and common editor files

.env-example

@@ -0,0 +1,39 @@
+# Core domain and contact settings
+TALER_DOMAIN=demogeld.example
+TALER_ADMIN_EMAIL=ops@demogeld.example
+LETSENCRYPT_CONTACT=mailto:ops@demogeld.example
+
+# PostgreSQL access
+TALER_DB_HOST=localhost
+TALER_DB_PORT=5432
+TALER_DB_ADMIN_USER=postgres
+TALER_DB_ADMIN_PASSWORD=CHANGE_ME
+TALER_EXCHANGE_DB=talerexchange
+TALER_EXCHANGE_DB_USER=taler_exchange
+TALER_EXCHANGE_DB_PASSWORD=CHANGE_ME
+TALER_MERCHANT_DB=talermerchant
+TALER_MERCHANT_DB_USER=taler_merchant
+TALER_MERCHANT_DB_PASSWORD=CHANGE_ME
+
+# Service hostnames
+TALER_EXCHANGE_HOST=exchange.demogeld.example
+TALER_MERCHANT_HOST=merchant.demogeld.example
+TALER_PAY_HOST=pay.demogeld.example
+WORDPRESS_HOST=www.demogeld.example
+
+# Package mirrors / versions
+TALER_PACKAGE_REPO=https://deb.taler.net/
+TALER_DISTRIBUTION=stable
+
+# TLS
+ACME_EMAIL=ops@demogeld.example
+
+# Optional WordPress database details (if managed here)
+WORDPRESS_DB_NAME=wp_demogeld
+WORDPRESS_DB_USER=wp_demogeld
+WORDPRESS_DB_PASSWORD=CHANGE_ME
+
+# Exchange master public key (never commit the real value)
+TALER_MASTER_PUBLIC_KEY=REPLACE_WITH_PUBLIC_KEY
+# Currency definition
+TALER_CURRENCY=DEMOGELD