Add detailed About panel to settings page

Introduces an About tab in the settings page displaying app, runtime, and system diagnostics. Adds IPC and preload bridge for about info, clipboard copy functionality, and external navigation for GitHub and Help links. Updates site-history.json with relevant links.

preload.js

@@ -84,4 +84,9 @@ const bookmarksAPI = {
 
 // Expose APIs to main world
 contextBridge.exposeInMainWorld('electronAPI', electronAPI);
-contextBridge.exposeInMainWorld('bookmarksAPI', bookmarksAPI);
+contextBridge.exposeInMainWorld('bookmarksAPI', bookmarksAPI);
+
+// Minimal about API for settings page
+contextBridge.exposeInMainWorld('aboutAPI', {
+  getInfo: () => ipcRenderer.invoke('get-about-info')
+});