begin implementing database. Down migrate doesnt work yet

src-tauri/migrations/0001_path_node_table.sql

@@ -0,0 +1,8 @@
+-- migrate:up
+CREATE TABLE PathNode (
+    id integer primary key,
+    title text,
+    description text
+)
+
+-- migrate:down

src-tauri/migrations/0002_node_exercise.sql

@@ -0,0 +1,8 @@
+-- migrate:up
+create table NodeExercise (
+    id integer primary key,
+    ex_type text,
+    content text
+)
+
+-- migrate:down