feat(message): add conversation notification mute feature

Add notification mute functionality for conversations with the following changes:

- Add notification_muted field to ConversationResponse and related DTOs
- Add notificationMutedMap to message store for tracking mute state
- Add setConversationNotificationMuted API method
- Integrate mute toggle in GroupInfoScreen and PrivateChatInfoScreen
- Skip system notifications for muted conversations
- Suppress vibration for muted conversations in WS handler
- Clean up selected mentions when @mentions are removed from text

Chore changes:
- Update PostCard bookmark icon from 'bookmark' to 'star'
- Refine card styles across AppsScreen, MaterialsScreen, and SubjectMaterialsScreen
- Improve week selector scrolling to center selected week in ScheduleScreen

src/types/dto.ts

@@ -266,6 +266,7 @@ export interface ConversationResponse {
   id: string;  // 雪花算法ID (使用string避免JavaScript精度丢失)
   type: ConversationType;
   is_pinned?: boolean;
+  notification_muted?: boolean;
   last_seq: number;
   last_message?: MessageResponse;
   last_message_at: string;
@@ -283,7 +284,8 @@ export interface ConversationResponse {
 export interface ConversationParticipantResponse {
   user_id: string;
   last_read_seq: number;
-  muted: boolean;
+  notification_muted: boolean;
+  is_pinned: boolean;
 }
 
 // 会话详情响应
@@ -291,6 +293,7 @@ export interface ConversationDetailResponse {
   id: string;
   type: ConversationType;
   is_pinned?: boolean;
+  notification_muted?: boolean;
   last_seq: number;
   last_message?: MessageResponse;
   last_message_at: string;