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/phoenixd/deploy_phoenixd_playbook.yml

@@ -253,7 +253,18 @@
     # ===========================================
     # 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 phoenixd health check script
+      when: uptime_kuma_enabled | default(false)
       copy:
         dest: "{{ phoenixd_healthcheck_script_path }}"
         content: |
@@ -340,6 +351,7 @@
         daemon_reload: yes
 
     - name: Enable and start phoenixd health check timer
+      when: uptime_kuma_enabled | default(false)
       systemd:
         name: "{{ phoenixd_healthcheck_service_name }}.timer"
         enabled: yes
@@ -349,6 +361,7 @@
     # Uptime Kuma Push Monitor Setup
     # ===========================================
     - name: Create Uptime Kuma push monitor setup script for phoenixd
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -443,6 +456,7 @@
         mode: "0755"
 
     - name: Create temporary config for push monitor setup
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -455,6 +469,7 @@
         mode: "0644"
 
     - name: Run Uptime Kuma push monitor setup
+      when: uptime_kuma_enabled | default(false)
       command: python3 /tmp/setup_phoenixd_monitor.py
       delegate_to: localhost
       become: no
@@ -468,6 +483,7 @@
       when: monitor_setup.stdout is defined
 
     - name: Read push URL from file
+      when: uptime_kuma_enabled | default(false)
       slurp:
         src: /tmp/phoenixd_push_url.txt
       delegate_to: localhost
@@ -489,6 +505,7 @@
       notify: Restart phoenixd health check timer
 
     - name: Clean up temporary files
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       file: