ha: add ntfy rest_command and Core update alert automation

- Add rest_command.ntfy_grafana_alerts in configuration.yaml
  (POST to https://ntfy.goattw.net/grafana-alerts)
- Add ha_core_version_update_alert automation in automations.yaml
  Triggers on update.home_assistant_core_update installed_version change
  Sends high-priority ntfy alert with old→new version and browser
  hard-refresh reminder (Ctrl+Shift+R / Cmd+Shift+R)

ha/configuration.yaml

@@ -0,0 +1,27 @@
+# Loads default set of integrations. Do not remove.
+default_config:
+
+# Load frontend themes from the themes folder
+frontend:
+  themes: !include_dir_merge_named themes
+
+automation: !include automations.yaml
+script: !include scripts.yaml
+scene: !include scenes.yaml
+http:
+  use_x_forwarded_for: true
+  trusted_proxies:
+    - 192.168.99.0/24 # <--- Trusts ANY device on your home network (Router, Server, Laptop)
+    - 172.16.0.0/12 # <--- Trusts all Docker containers
+    - 127.0.0.1 # <--- Localhost
+
+rest_command:
+  ntfy_grafana_alerts:
+    url: https://ntfy.goattw.net/grafana-alerts
+    method: POST
+    content_type: "text/plain"
+    payload: "{{ message }}"
+    headers:
+      Title: "{{ title | default('Home Assistant') }}"
+      Priority: "{{ priority | default('default') }}"
+      Tags: "{{ tags | default('house') }}"