refactor(data): consolidate data layer under services namespace

- Move src/data/{api,dto,schemas} directories to src/data/services/*
- Update all relative imports across the codebase to reference new paths
- Use CSS color tokens for splash button gradient in splash-button.module.css
- Add responsive sizes attribute to splash background image
- Add JSDoc documentation to splash-background component referencing original Dart implementation

src/data/dto/user/index.ts

@@ -1,12 +0,0 @@
-/**
- * @file Automatically generated by barrelsby.
- */
-
-export * from "./avatar_data";
-export * from "./credits_data";
-export * from "./credits_history_data";
-export * from "./personality_traits";
-export * from "./recent_memory";
-export * from "./update_profile_request";
-export * from "./user";
-export * from "./user_stats_response";