uptime-kuma: add uptime_kuma_enabled flag and make monitoring blocks inert

Removing the credentials would otherwise break these playbooks mid-deploy: they
template uptime_kuma_password with no assert to stop them first. 100 tasks are
now guarded by uptime_kuma_enabled (false), so deployments run normally and the
monitoring sections skip. A further 28 tasks were already self-guarding on
monitor_setup/push_url being defined; verified that a skipped task's registered
variable makes those skip cleanly rather than error.

The blocks are kept on purpose — the health-check logic is the durable part and
should be rewired to whatever replaces Uptime Kuma.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

ansible/services/datum-gateway/deploy_datum_gateway_playbook.yml

@@ -206,7 +206,18 @@
     # ===========================================
     # Health Check Script + Systemd Timer
     # ===========================================
+    # ═════════════════════════════════════════════════════════════════════════
+    # DEPRECATED — Uptime Kuma was decommissioned on 2026-09-11.
+    #
+    # Every task below is inert: uptime_kuma_enabled is false in
+    # group_vars/all/main.yml, so they all skip and the deployment above still
+    # runs normally. Kept because the health-check logic is the durable part —
+    # when a replacement exists, rewire the push transport and flip the flag.
+    #
+    # What was being monitored: archive/uptime_kuma/MONITORS.md
+    # ═════════════════════════════════════════════════════════════════════════
     - name: Create DATUM Gateway health check script
+      when: uptime_kuma_enabled | default(false)
       copy:
         dest: /usr/local/bin/datum-gateway-healthcheck-push.sh
         content: |
@@ -287,6 +298,7 @@
         daemon_reload: yes
 
     - name: Enable and start datum-gateway health check timer
+      when: uptime_kuma_enabled | default(false)
       systemd:
         name: datum-gateway-healthcheck.timer
         enabled: yes
@@ -296,6 +308,7 @@
     # Uptime Kuma Push Monitor Setup
     # ===========================================
     - name: Create Uptime Kuma push monitor setup script for DATUM Gateway
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -396,6 +409,7 @@
         mode: "0755"
 
     - name: Create temporary config for push monitor setup
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -408,6 +422,7 @@
         mode: "0644"
 
     - name: Run Uptime Kuma push monitor setup
+      when: uptime_kuma_enabled | default(false)
       command: python3 /tmp/setup_datum_gateway_monitor.py
       delegate_to: localhost
       become: no
@@ -421,6 +436,7 @@
       when: monitor_setup.stdout is defined
 
     - name: Read push URL from file
+      when: uptime_kuma_enabled | default(false)
       slurp:
         src: /tmp/datum_gateway_push_url.txt
       delegate_to: localhost
@@ -442,6 +458,7 @@
       notify: Restart datum-gateway health check timer
 
     - name: Clean up temporary files
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       file:
@@ -460,6 +477,7 @@
         daemon_reload: yes
 
     - name: Restart datum-gateway health check timer
+      when: uptime_kuma_enabled | default(false)
       systemd:
         name: datum-gateway-healthcheck.timer
         state: restarted
@@ -539,6 +557,7 @@
         msg: "{{ caddy_reload.stdout_lines + caddy_reload.stderr_lines }}"
 
     - name: Display DATUM Gateway dashboard URL
+      when: uptime_kuma_enabled | default(false)
       debug:
         msg: "DATUM Gateway dashboard: https://{{ datum_gateway_domain }}"
 
@@ -546,6 +565,7 @@
     # Uptime Kuma HTTP Monitor for Public Dashboard
     # ===========================================
     - name: Create Uptime Kuma HTTP monitor setup script for DATUM dashboard
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -621,6 +641,7 @@
         mode: "0755"
 
     - name: Create temporary config for HTTP monitor
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -634,6 +655,7 @@
         mode: "0644"
 
     - name: Run Uptime Kuma HTTP monitor setup
+      when: uptime_kuma_enabled | default(false)
       command: python3 /tmp/setup_datum_http_monitor.py
       delegate_to: localhost
       become: no
@@ -647,6 +669,7 @@
       when: http_monitor_setup.stdout is defined
 
     - name: Clean up HTTP monitor temporary files
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       file:
@@ -733,6 +756,7 @@
       ignore_errors: yes
 
     - name: Display public Stratum endpoint
+      when: uptime_kuma_enabled | default(false)
       debug:
         msg: "DATUM Stratum public endpoint: {{ ansible_host }}:{{ datum_gateway_stratum_port }}"
 
@@ -740,6 +764,7 @@
     # Uptime Kuma TCP Monitor for Public Stratum
     # ===========================================
     - name: Create Uptime Kuma TCP monitor setup script for Stratum
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -816,6 +841,7 @@
         mode: "0755"
 
     - name: Create temporary config for Stratum TCP monitor
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -830,6 +856,7 @@
         mode: "0644"
 
     - name: Run Uptime Kuma TCP monitor setup
+      when: uptime_kuma_enabled | default(false)
       command: python3 /tmp/setup_datum_stratum_tcp_monitor.py
       delegate_to: localhost
       become: no
@@ -843,6 +870,7 @@
       when: tcp_monitor_setup.stdout is defined
 
     - name: Clean up Stratum TCP monitor temporary files
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       file: