feat(theme): 新增主题详情查询接口

支持根据主题ID和用户ID查询主题详情，包含购买状态

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

@@ -75,4 +75,12 @@ public class ThemesController {
         return ResultUtils.success(result);
     }
 
+    @GetMapping("/detail")
+    @Operation(summary = "查询主题详情", description = "根据主题ID查询主题详情")
+    public BaseResponse<KeyboardThemesRespVO> getThemeDetail(@RequestParam Long themeId) {
+        Long userId = StpUtil.getLoginIdAsLong();
+        KeyboardThemesRespVO result = themesService.getThemeDetail(themeId, userId);
+        return ResultUtils.success(result);
+    }
+
 }