feat(grafana): provision disk alerts to ntfy

Provision Grafana Unified Alerting as code: ntfy webhook contact point
(?template=grafana), notification policy tree, and cumulative disk tiers
for HDD temperature (48-60C, <20C) plus ZFS/filesystem capacity. Lower the
smartctl exporter interval to 30m for alert responsiveness.

roles/grafana/tasks/main.yml

@@ -269,6 +269,70 @@
     mode: "0644"
   notify: Restart grafana
 
+# Alerting provisioning (Unified Alerting -> ntfy webhook)
+- name: Validate ntfy alerting settings are set
+  ansible.builtin.assert:
+    that:
+      - grafana_ntfy_webhook_url is defined
+      - grafana_ntfy_webhook_url | length > 0
+      - grafana_ntfy_token is defined
+      - grafana_ntfy_token | length > 0
+    fail_msg: |
+      grafana_alerting_enabled is true but grafana_ntfy_webhook_url / grafana_ntfy_token are not set.
+      See roles/grafana/defaults/main.yml for configuration instructions.
+    success_msg: "ntfy alerting settings validated"
+  when: grafana_alerting_enabled
+
+- name: Ensure Grafana alerting provisioning directory exists
+  ansible.builtin.file:
+    path: "{{ grafana_provisioning_path }}/alerting"
+    state: directory
+    owner: "{{ grafana_user }}"
+    group: "{{ grafana_group }}"
+    mode: "0755"
+  when: grafana_alerting_enabled
+
+- name: Deploy Grafana alerting contact points
+  ansible.builtin.template:
+    src: alerting-contact-points.yaml.j2
+    dest: "{{ grafana_provisioning_path }}/alerting/contact-points.yaml"
+    owner: "{{ grafana_user }}"
+    group: "{{ grafana_group }}"
+    mode: "0600"
+  when: grafana_alerting_enabled
+  notify: Restart grafana
+
+- name: Deploy Grafana alerting notification policies
+  ansible.builtin.copy:
+    src: alerting-policies.yaml
+    dest: "{{ grafana_provisioning_path }}/alerting/policies.yaml"
+    owner: "{{ grafana_user }}"
+    group: "{{ grafana_group }}"
+    mode: "0644"
+  when: grafana_alerting_enabled
+  notify: Restart grafana
+
+- name: Deploy Grafana disk alert rules
+  ansible.builtin.copy:
+    src: alerting-rules.yaml
+    dest: "{{ grafana_provisioning_path }}/alerting/rules.yaml"
+    owner: "{{ grafana_user }}"
+    group: "{{ grafana_group }}"
+    mode: "0644"
+  when: grafana_alerting_enabled
+  notify: Restart grafana
+
+- name: Remove Grafana alerting provisioning when disabled
+  ansible.builtin.file:
+    path: "{{ grafana_provisioning_path }}/alerting/{{ item }}"
+    state: absent
+  loop:
+    - contact-points.yaml
+    - policies.yaml
+    - rules.yaml
+  when: not grafana_alerting_enabled
+  notify: Restart grafana
+
 # Service management
 - name: Enable and start Grafana service
   ansible.builtin.systemd: