feat: prepare six-lesson trial backend with reliable rewards and operations

Co-authored-by: Cursor <cursoragent@cursor.com>

src/users/users.service.ts

@@ -90,10 +90,12 @@ export class UsersService {
   }
 
   updateProfile(userId: string, name: string): MeResponse {
-    const state = this.getUserState(userId)
-    state.name = name.trim()
-    this.saveUserState(state)
-    return this.toMeResponse(state)
+    return this.database.transaction(() => {
+      const state = this.getUserState(userId)
+      state.name = name.trim()
+      this.saveUserState(state)
+      return this.toMeResponse(state)
+    })
   }
 
   private parseStateJson(raw: string, userId: string): UserState {