feat(DiaryDateActivity, DiaryView): integrate groupId for enhanced activity management

- Added `groupId` field to the DiaryDateActivity model to support group-specific activities.
- Updated create and update methods in DiaryDateActivityService to handle groupId, ensuring proper validation and association with groups.
- Enhanced DiaryView component to allow selection of groups for activities, improving user experience and activity organization.
- Implemented filtering logic in DiaryView to display activities based on selected group, enhancing data clarity and usability.

backend/migrations/20260508_add_group_id_to_diary_date_activities_and_migrate_group_activity.sql

@@ -0,0 +1,30 @@
+ALTER TABLE `diary_date_activities`
+    ADD COLUMN `group_id` INT NULL AFTER `predefined_activity_id`,
+    ADD CONSTRAINT `fk_diary_date_activities_group_id`
+        FOREIGN KEY (`group_id`) REFERENCES `group`(`id`)
+        ON DELETE SET NULL
+        ON UPDATE CASCADE;
+
+INSERT INTO `diary_date_activities` (
+    `diary_date_id`,
+    `is_timeblock`,
+    `predefined_activity_id`,
+    `group_id`,
+    `duration`,
+    `duration_text`,
+    `order_id`,
+    `created_at`,
+    `updated_at`
+)
+SELECT
+    d.`diary_date_id`,
+    0 AS `is_timeblock`,
+    ga.`custom_activity` AS `predefined_activity_id`,
+    ga.`group_id`,
+    ga.`duration`,
+    ga.`duration_text`,
+    (d.`order_id` * 100) + COALESCE(ga.`order_id`, 1) AS `order_id`,
+    COALESCE(ga.`created_at`, NOW()) AS `created_at`,
+    COALESCE(ga.`updated_at`, NOW()) AS `updated_at`
+FROM `group_activity` ga
+INNER JOIN `diary_date_activities` d ON d.`id` = ga.`diary_date_activity`;