feat(ansible/base): configure Hetzner floating IP via systemd service

Add hetzner-floating-ip.service systemd unit to base role so that
the floating IP is bound to eth0 on every boot. The task is
conditional (runs only when hetzner_floating_ip is defined in
host_vars). Add 49.12.116.113 as the floating IP for iklim-app-01
in test host_vars.

ansible/roles/base/tasks/main.yml

@@ -54,3 +54,29 @@
 - name: Set keyboard layout to Turkish Q
   ansible.builtin.command: localectl set-keymap trq
   when: "'trq' not in localectl_status.stdout"
+
+- name: Deploy Hetzner floating IP systemd service
+  ansible.builtin.copy:
+    dest: /etc/systemd/system/hetzner-floating-ip.service
+    mode: "0644"
+    content: |
+      [Unit]
+      Description=Hetzner Floating IP
+      After=network.target
+
+      [Service]
+      Type=oneshot
+      ExecStart=/sbin/ip addr replace {{ hetzner_floating_ip }}/32 dev {{ hetzner_primary_interface | default('eth0') }}
+      RemainAfterExit=yes
+
+      [Install]
+      WantedBy=multi-user.target
+  when: hetzner_floating_ip is defined
+
+- name: Enable and start Hetzner floating IP service
+  ansible.builtin.systemd:
+    name: hetzner-floating-ip
+    enabled: yes
+    state: started
+    daemon_reload: yes
+  when: hetzner_floating_ip is defined

ansible/test/host_vars/iklim-app-01/vars.yml

@@ -0,0 +1,2 @@
+hetzner_floating_ip: "49.12.116.113"
+hetzner_primary_interface: "eth0"