add record size to hourly snapshot page

db/schema.sql

@@ -70,7 +70,8 @@ CREATE TABLE IF NOT EXISTS snapshot_registry (
 	"id" INTEGER PRIMARY KEY AUTOINCREMENT,
 	"snapshot_type" TEXT NOT NULL,
 	"table_name" TEXT NOT NULL UNIQUE,
-	"snapshot_time" INTEGER NOT NULL
+	"snapshot_time" INTEGER NOT NULL,
+	"snapshot_count" BIGINT NOT NULL DEFAULT 0
 );
 
 -- The following tables are declared for sqlc type-checking only.