feat(themes): 支持主题标签数组存储与按风格查询

- 新增 StringArrayTypeHandler 实现 PostgreSQL text[] ↔ Java String[] 映射
- 将 theme_tag 字段类型由 VARCHAR 改为 ARRAY，实体与 VO 同步调整为 String[]
- 移除废弃的 selectAllThemes 方法，统一使用 selectThemesByStyle(Long)
- 9999 风格 ID 保留查询全部上架主题逻辑，其余按风格过滤
- 开放 /themes/listByStyle 接口免鉴权，并修正 theme_status=true 查询条件

src/main/java/com/yolo/keyborad/controller/ThemesController.java

@@ -30,9 +30,6 @@ public class ThemesController {
     @Resource
     private KeyboardThemesService themesService;
 
-    @Resource
-    private KeyboardThemesService keyboardThemesService;
-
     @Resource
     private KeyboardThemeStylesService keyboardThemeStylesService;