Add About page for Khoj to Desktop app. Expose it via system tray

- Pass current khoj version from package.json to about page via
  electron IPC between backend js and frontend page
- Update Khoj information in default About screen as well, in case
  it's exposed anywhere else

src/interface/desktop/utils.js

@@ -12,3 +12,15 @@ I am ✨Khoj✨, your open-source, personal AI copilot.
 See my source code at https://github.com/khoj-ai/khoj
 Read my operating manual at https://docs.khoj.dev
 `);
+
+
+window.appInfoAPI.getInfo((_, info) => {
+    let khojVersionElement = document.getElementById("about-page-version");
+    if (khojVersionElement) {
+        khojVersionElement.innerHTML = `<code>${info.version}</code>`;
+    }
+    let khojTitleElement = document.getElementById("about-page-title");
+    if (khojTitleElement) {
+        khojTitleElement.innerHTML = '<b>Khoj for ' + (info.platform === 'win32' ? 'Windows' : info.platform === 'darwin' ? 'macOS' : 'Linux') + '</b>';
+    }
+});