Change db format a little

backend/migrations/1_initial.sql

@@ -1,7 +1,9 @@
 create table users
 (
     id   integer primary key,
-    name text not null
+    name text not null,
+    weight real not null default 1.0,
+    balance integer not null default 0
 ) strict;
 
 create table history
@@ -18,7 +20,7 @@ create table allowances
 	user_id integer not null,
     name text not null,
     target integer not null,
-    progress integer not null,
+    progress integer not null default 0,
     weight real not null
 );