Create initial backend (#7)

Closes #3

Reviewed-on: #7

backend/migrations/1_initial.sql

@@ -0,0 +1,32 @@
+create table users
+(
+    id   integer primary key,
+    name text not null
+) strict;
+
+create table history
+(
+    id integer primary key,
+    user_id integer not null,
+    date date not null,
+    amount integer not null
+);
+
+create table goals
+(
+    id integer primary key,
+    name text not null,
+    target integer not null,
+    progress integer not null,
+    weight real not null
+);
+
+create table tasks
+(
+    id integer primary key,
+    name text not null,
+    reward integer not null,
+    assigned integer
+);
+
+insert into users (name) values ('Seeseemelk'), ('Huffle');