split housekeeping jobs to separate scheduled tasks on longer cooldown intervals, add table to record task execution timestamps, bump schema

sql/pgsql/migrations/150.sql

@@ -0,0 +1,5 @@
+create table ttrss_scheduled_tasks(
+   id serial not null primary key,
+   task_name varchar(250) unique not null,
+   last_rc integer not null,
+   last_run timestamp not null default NOW());

sql/pgsql/schema.sql

@@ -1,3 +1,4 @@
+drop table if exists ttrss_scheduled_tasks;
 drop table if exists ttrss_error_log;
 drop table if exists ttrss_plugin_storage;
 drop table if exists ttrss_linked_feeds;
@@ -394,4 +395,10 @@ create table ttrss_error_log(
 	context text not null,
 	created_at timestamp not null);
 
+create table ttrss_scheduled_tasks(
+	id serial not null primary key,
+   task_name varchar(250) unique not null,
+   last_rc integer not null,
+   last_run timestamp not null default NOW());
+
 commit;