feat: convert WSL Linux paths to Windows UNC paths when opening binary files

Adds open_binary_file Tauri command that translates WSL Linux-style paths
(e.g. /tmp/mcp_output_abc123.pdf) to Windows UNC paths via wslpath -w
before opening, so binary file links work correctly on Windows/WSL.
Non-Windows platforms pass the path through unchanged. Markdown.svelte
now invokes this command instead of calling openPath directly.

src/lib/components/Markdown.svelte

@@ -2,7 +2,8 @@
   import { marked } from "marked";
   import hljs from "highlight.js";
   import { onMount } from "svelte";
-  import { openUrl, openPath } from "@tauri-apps/plugin-opener";
+  import { openUrl } from "@tauri-apps/plugin-opener";
+  import { invoke } from "@tauri-apps/api/core";
   import { clipboardStore } from "$lib/stores/clipboard";
   import { linkifyFilePaths } from "$lib/utils/filePaths";
 
@@ -148,7 +149,7 @@
 
     const filePath = anchor.dataset.filepath;
     if (filePath) {
-      void openPath(filePath);
+      void invoke("open_binary_file", { path: filePath });
       return;
     }
 

src/lib/components/Markdown.test.ts

@@ -9,7 +9,8 @@
  * - [ ] Code blocks render with syntax highlighting and a copy button
  * - [ ] ||spoiler text|| renders as a hidden span revealed on click
  * - [ ] Search query highlights matching text in non-code content
- * - [ ] Links open in the system browser via the Tauri opener
+ * - [ ] Regular links open in the system browser via the Tauri opener
+ * - [ ] Binary file links invoke open_binary_file (WSL-path-aware) instead of openPath
  */
 
 import { describe, it, expect } from "vitest";