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/vaultwarden/deploy_vaultwarden_playbook.yml

@@ -111,7 +111,18 @@
     - name: Reload Caddy to apply new config
       command: systemctl reload caddy
 
+    # ═════════════════════════════════════════════════════════════════════════
+    # 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 Uptime Kuma monitor setup script for Vaultwarden
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -191,6 +202,7 @@
         mode: '0755'
 
     - name: Create temporary config for monitor setup
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       copy:
@@ -204,6 +216,7 @@
         mode: '0644'
 
     - name: Run Uptime Kuma monitor setup
+      when: uptime_kuma_enabled | default(false)
       command: python3 /tmp/setup_vaultwarden_monitor.py
       delegate_to: localhost
       become: no
@@ -212,6 +225,7 @@
       ignore_errors: yes
 
     - name: Clean up temporary files
+      when: uptime_kuma_enabled | default(false)
       delegate_to: localhost
       become: no
       file: