home-assistant: Add (back) event-snapshot.sh

When transitioning to the ConfigMap for maintaining Home Assistant YAML
configuration, I did not bring the `event-snapshot.sh` script because I
thought it was no longer in use.  It turns out I was mistaken; it is
used by the driveway camera alerts.

home-assistant/event-snapshot.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+curl -fsSL -o /tmp/snapshot.jpg "http://frigate.pyrocufflink.blue:5000/api/events/$1/snapshot.jpg"

home-assistant/kustomization.yaml

@@ -23,6 +23,7 @@ configMapGenerator:
 - name: home-assistant
   files:
   - configuration.yaml
+  - event-snapshot.sh
   - groups.yaml
   - shell-command.yaml
   options:

home-assistant/shell-command.yaml

@@ -1,2 +1,5 @@
+event_snapshot: >-
+  sh /run/config/event-snapshot.sh {{ event_id }}
+
 restart_diddy_mopidy: >-
   ssh -i /config/homeassistant-ssh.pem -oUserKnownHostsFile=/config/ssh_known_hosts -oBatchMode=yes pi@diddy.pyrocufflink.red restart-mopidy