feat(automations): add per-host maintenance mode and recurring schedules (#1521)

plugins/automations/migrations/sqlite/0003_host_maintenance.sql

@@ -0,0 +1,12 @@
+-- automations 0003: host_maintenance
+-- Generated by termix-plugin migrations. Review before committing.
+
+CREATE TABLE IF NOT EXISTS "p_automations_host_maintenance" (
+  "id" integer PRIMARY KEY AUTOINCREMENT,
+  "user_id" text NOT NULL,
+  "host_id" integer NOT NULL,
+  "state" text NOT NULL,
+  FOREIGN KEY ("user_id") REFERENCES "users" ("id") ON DELETE CASCADE,
+  FOREIGN KEY ("host_id") REFERENCES "ssh_data" ("id") ON DELETE CASCADE
+);
+CREATE UNIQUE INDEX IF NOT EXISTS "maintenance_host_owner" ON "p_automations_host_maintenance" ("user_id", "host_id");