✨ 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

roles/postgres/tasks/main.yml

@@ -0,0 +1,53 @@
+---
+- name: Ensure PostgreSQL server packages are present
+  ansible.builtin.apt:
+    name:
+      - postgresql
+      - python3-psycopg2
+    state: present
+
+- name: Ensure PostgreSQL service is running
+  ansible.builtin.service:
+    name: postgresql
+    state: started
+    enabled: true
+
+- name: Create exchange database user
+  community.postgresql.postgresql_user:
+    name: "{{ taler_config.db.exchange.user }}"
+    password: "{{ taler_config.db.exchange.password | default(omit) }}"
+    login_user: "{{ taler_config.db.admin_user }}"
+    login_password: "{{ taler_config.db.admin_password | default(omit) }}"
+    login_host: "{{ taler_config.db.host }}"
+    port: "{{ taler_config.db.port }}"
+  no_log: true
+
+- name: Create merchant database user
+  community.postgresql.postgresql_user:
+    name: "{{ taler_config.db.merchant.user }}"
+    password: "{{ taler_config.db.merchant.password | default(omit) }}"
+    login_user: "{{ taler_config.db.admin_user }}"
+    login_password: "{{ taler_config.db.admin_password | default(omit) }}"
+    login_host: "{{ taler_config.db.host }}"
+    port: "{{ taler_config.db.port }}"
+  no_log: true
+
+- name: Ensure exchange database exists
+  community.postgresql.postgresql_db:
+    name: "{{ taler_config.db.exchange.name }}"
+    owner: "{{ taler_config.db.exchange.user }}"
+    encoding: UTF8
+    login_user: "{{ taler_config.db.admin_user }}"
+    login_password: "{{ taler_config.db.admin_password | default(omit) }}"
+    login_host: "{{ taler_config.db.host }}"
+    port: "{{ taler_config.db.port }}"
+
+- name: Ensure merchant database exists
+  community.postgresql.postgresql_db:
+    name: "{{ taler_config.db.merchant.name }}"
+    owner: "{{ taler_config.db.merchant.user }}"
+    encoding: UTF8
+    login_user: "{{ taler_config.db.admin_user }}"
+    login_password: "{{ taler_config.db.admin_password | default(omit) }}"
+    login_host: "{{ taler_config.db.host }}"
+    port: "{{ taler_config.db.port }}"