fix: use backend command to read memory files for WSL compatibility

The frontend was using Tauri's `readTextFile` plugin which enforces
scope restrictions and doesn't work with WSL paths on Windows.

Changed to use our `read_file_content` backend command which:
- Already handles WSL paths correctly on Windows
- Works with absolute paths on all platforms
- Bypasses Tauri's filesystem scope restrictions
- Matches the pattern used throughout the app for file operations

This fixes the "forbidden path" error when trying to read memory
files on Windows whilst maintaining functionality on Linux/Mac.

✨ This fix was created by Hikari~ 🌸

src/lib/components/MemoryBrowserPanel.svelte

@@ -1,7 +1,6 @@
 <script lang="ts">
   import { onMount } from "svelte";
   import { invoke } from "@tauri-apps/api/core";
-  import { readTextFile } from "@tauri-apps/plugin-fs";
   import Markdown from "./Markdown.svelte";
 
   let memoryFiles: string[] = $state([]);
@@ -33,7 +32,8 @@
     isLoading = true;
     error = null;
     try {
-      const content = await readTextFile(filePath);
+      // Use our backend command instead of Tauri plugin to handle WSL paths
+      const content = await invoke<string>("read_file_content", { path: filePath });
       fileContent = content;
       selectedFile = filePath;
     } catch (e) {