refactor: 重构 schemas 结构，统一枚举定义

docs/protocols/calendar/schedule-items.md

@@ -28,10 +28,10 @@ Base URL: `/api/v1/schedule-items`
 | 值 | 说明 |
 |---|---|
 | `active` | 进行中 |
-| `completed` | 已完成 |
-| `canceled` | 已取消 |
 | `archived` | 已归档 |
 
+兼容策略：历史数据中若存在 `completed` 或 `canceled`，服务端统一按 `archived` 语义处理；新写入仅允许 `active` 或 `archived`。
+
 ### ScheduleItemSourceType
 
 | 值 | 说明 |
@@ -96,7 +96,7 @@ Base URL: `/api/v1/schedule-items`
   "end_at": "datetime | null (必须包含时区)",
   "timezone": "string | null (IANA 时区)",
   "metadata": "ScheduleItemMetadata | null",
-  "status": "ScheduleItemStatus | null"
+  "status": "ScheduleItemStatus | null (active | archived)"
 }
 ```
 
@@ -116,7 +116,7 @@ Base URL: `/api/v1/schedule-items`
   "source_type": "ScheduleItemSourceType",
   "created_at": "datetime",
   "updated_at": "datetime",
-  "permission": "int",
+  "permission": "int (位掩码: 1=view, 2=invite, 4=edit)",
   "is_owner": "boolean"
 }
 ```
@@ -132,6 +132,11 @@ Base URL: `/api/v1/schedule-items`
 }
 ```
 
+说明：`permission_view`、`permission_edit`、`permission_invite` 为布尔值，内部会转换为位掩码整数：
+- `permission_view = 1`
+- `permission_invite = 2`
+- `permission_edit = 4`
+
 ### ScheduleItemShareResponse
 
 ```json