fix: maintenance index name, shared host read only view and badge polling

plugins/automations/migrations/postgres/0004_rename_maintenance_index.sql

@@ -0,0 +1,5 @@
+-- automations 0004: rename_maintenance_index
+-- Renames the maintenance index to the idx_ pattern every other index uses.
+
+CREATE UNIQUE INDEX IF NOT EXISTS "idx_automation_maintenance_host_owner" ON "p_automations_host_maintenance" ("user_id", "host_id");
+DROP INDEX IF EXISTS "maintenance_host_owner";