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/forgejo-runner/deploy_forgejo_runner_playbook.yml

@@ -147,7 +147,18 @@
       register: runner_active
       changed_when: false
 
+    # ═════════════════════════════════════════════════════════════════════════
+    # 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: Assert runner is running
+      when: uptime_kuma_enabled | default(false)
       assert:
         that:
           - runner_active.stdout == "active"
@@ -155,6 +166,7 @@
 
     # ── 10. Set up Uptime Kuma push monitor ────────────────────────────
     - name: Create Uptime Kuma push monitor setup script
+      when: uptime_kuma_enabled | default(false)
       copy:
         dest: /tmp/setup_forgejo_runner_monitor.py
         content: |
@@ -238,6 +250,7 @@
       become: no
 
     - name: Run Uptime Kuma push monitor setup
+      when: uptime_kuma_enabled | default(false)
       command: >
         {{ ansible_playbook_python }}
         /tmp/setup_forgejo_runner_monitor.py
@@ -256,10 +269,12 @@
       changed_when: false
 
     - name: Parse monitor setup result
+      when: uptime_kuma_enabled | default(false)
       set_fact:
         monitor_info_parsed: "{{ monitor_setup_result.stdout | from_json }}"
 
     - name: Set push URL
+      when: uptime_kuma_enabled | default(false)
       set_fact:
         uptime_kuma_push_url: "{{ uptime_kuma_api_url }}/api/push/{{ monitor_info_parsed.push_token }}"
 
@@ -272,6 +287,7 @@
         mode: '0755'
 
     - name: Create forgejo-runner healthcheck script
+      when: uptime_kuma_enabled | default(false)
       copy:
         dest: "{{ healthcheck_script_path }}"
         content: |
@@ -385,6 +401,7 @@
           Timeout: {{ healthcheck_timeout_seconds }}s
 
     - name: Clean up temporary monitor setup script
+      when: uptime_kuma_enabled | default(false)
       file:
         path: /tmp/setup_forgejo_runner_monitor.py
         state: absent