feat: trigger for ctime on usertitle update

sql/migrations/000001_init.up.sql

@@ -87,7 +87,7 @@ CREATE TABLE usertitles (
     status              usertitle_status_t  NOT NULL,
     rate                int                 CHECK (rate > 0 AND rate <= 10),
     review_id           bigint              REFERENCES reviews (id),
-    ctime               timestamptz
+    ctime               timestamptz         NOT NULL DEFAULT now()
     -- // TODO: series status
 );
 
@@ -169,4 +169,17 @@ EXECUTE FUNCTION update_title_rating();
 CREATE TRIGGER trg_notify_new_signal
 AFTER INSERT ON signals
 FOR EACH ROW
-EXECUTE FUNCTION notify_new_signal();
+EXECUTE FUNCTION notify_new_signal();
+
+CREATE OR REPLACE FUNCTION set_ctime()
+RETURNS TRIGGER AS $$
+BEGIN
+    NEW.ctime = now();
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER set_ctime_on_update
+BEFORE UPDATE ON usertitles
+FOR EACH ROW
+EXECUTE FUNCTION set_ctime();