Add control entities: box to-do list, skip switch, donate button, subscriptions

The to-do list exists so Home Assistant's own conversation agent can manage the
order through HassListAddItem rather than through anything bespoke. Skip is a
switch because skipped/not-skipped is state worth reading back; donate is a
button because it cannot be undone. Un-skip raises rather than guessing at an
endpoint that has never been observed.

Fixes subscription parsing, which matched the heading row and so reported zero
on an account that has one.

custom_components/freshharvest/const.py

@@ -10,3 +10,7 @@ DOMAIN = "freshharvest"
 # schedules change on the order of days, and the customization cutoff is the
 # only time-sensitive value.
 UPDATE_INTERVAL = timedelta(hours=6)
+
+# Fired after every write action so automations can notify on success or
+# failure. Data: domain, entry_id, action, success, target, detail.
+EVENT_ACTION = "freshharvest_action"