Fix datetime bug

hooks/useFilesystem.ts

@@ -1,9 +1,9 @@
-import { useState, useEffect, useCallback } from 'react';
-import AsyncStorage from '@react-native-async-storage/async-storage';
-import * as FileSystem from 'expo-file-system';
 import { DATA_DIRECTORY_URI_KEY } from '@/constants/Settings';
-import { StorageAccessFramework } from 'expo-file-system';
+import AsyncStorage from '@react-native-async-storage/async-storage';
 import { format } from 'date-fns';
+import * as FileSystem from 'expo-file-system';
+import { StorageAccessFramework } from 'expo-file-system';
+import { useCallback, useEffect, useState } from 'react';
 
 interface FileEntry {
     name: string;
@@ -22,7 +22,7 @@ interface FileInfoWithSize {
     size: number;
 }
 
-function datetimeFromFilename(filename: string): string {
+function datetimeFromFilename(filename: string): Date {
     const match = filename.match(/(\d+)-(\d+)-(\d+)-(\d+)-(\d+)-(\d+)\.md$/);
     if (match) {
         const [_, year, month, day, hour, minute, second] = match;
@@ -33,9 +33,9 @@ function datetimeFromFilename(filename: string): string {
             parseInt(hour),
             parseInt(minute),
             parseInt(second)
-        ).toISOString();
+        );
     }
-    return new Date().toISOString();
+    return new Date();
 }
 
 export function prettyName(uri: string | null, options: PrettyNameOptions = {}) {
@@ -118,7 +118,7 @@ export function useFileSystem() {
             }
             markdownFiles.sort((a, b) => b.datetime.getTime() - a.datetime.getTime()); // Sort by datetime descending
             setFiles(markdownFiles);
-            setDirectorySize(totalSize);
+            setDirectorySize(Math.round((totalSize / 1024 / 1024) * 1000) / 1000); // Convert to MB
         } catch (error) {
             console.error('Error loading files:', error);
         }