fix(PostImages, CreatePostScreen): adjust image gap for improved layout consistency

- Reduced image gap in PostImages and CreatePostScreen components from 12 to 4 (desktop) and 8 to 2 (mobile) for better spacing.
- Updated ImageGrid component to modify grid item widths for enhanced layout.
- Refactored PostRepository to improve local caching logic, ensuring non-blocking UI updates during cache writes.
- Introduced saveConversationsWithRelatedCache function to streamline conversation, user, and group data saving in the database.

src/services/messageService.ts

@@ -25,9 +25,7 @@ import {
   getConversationCache,
   getConversationListCache,
   saveConversationCache,
-  saveConversationsCache,
-  saveGroupsCache,
-  saveUsersCache,
+  saveConversationsWithRelatedCache,
   updateConversationCacheUnreadCount,
 } from './database';
 
@@ -48,18 +46,14 @@ class MessageService {
     list: ConversationResponse[]
   ): Promise<void> {
     if (!list.length) return;
-    await saveConversationsCache(list);
-    await saveUsersCache(
-      list.flatMap(conv => [
-        ...(conv.participants || []),
-        ...(conv.last_message?.sender ? [conv.last_message.sender] : []),
-      ])
-    );
-    await saveGroupsCache(
-      list
-        .map(conv => conv.group)
-        .filter((group): group is NonNullable<typeof group> => Boolean(group))
-    );
+    const users = list.flatMap(conv => [
+      ...(conv.participants || []),
+      ...(conv.last_message?.sender ? [conv.last_message.sender] : []),
+    ]);
+    const groups = list
+      .map(conv => conv.group)
+      .filter((group): group is NonNullable<typeof group> => Boolean(group));
+    await saveConversationsWithRelatedCache(list, users, groups);
   }
 
   /** offset 会话列表单页：请求 + 落库 */