Add created_lessons table for AI-generated lessons

src/lib/db.ts

@@ -133,16 +133,9 @@ function migrate(db: Database.Database) {
     CREATE INDEX IF NOT EXISTS idx_drawings_user ON drawings(user_id);
     CREATE INDEX IF NOT EXISTS idx_drawings_progress ON drawings(user_id, level, sublevel, status);
     CREATE INDEX IF NOT EXISTS idx_completions_user ON completions(user_id);
-  `);
 
-  // Profile fields (added later — safe for existing databases)
-  addColumn(db, "users", "display_name", "TEXT");
-  addColumn(db, "users", "avatar", "TEXT");
-}
-
-export function getDb(): Database.Database {
-  if (!global.__drawitDb) {
-    global.__drawitDb = createConnection();
-  }
-  return global.__drawitDb;
-}
+    -- AI "Create" feature: a Creator types a subject; ComfyUI makes line art; we vectorize it into a lesson.
+    CREATE TABLE IF NOT EXISTS created_lessons (
+      id           INTEGER PRIMARY KEY AUTOINCREMENT,
+      user_id      INTEGER REFERENCES users(id) ON DELETE CASCADE,  -- null once promoted to global
+      level