feat: add browser extension integration hooks

- Add lmExtensionHandled check to prevent duplicate downloads
- Add lm:refreshVersions event listener for extension-triggered refresh
- Expose downloadManager to window for extension access

static/js/components/shared/ModelVersionsTab.js

@@ -1142,6 +1142,11 @@ export function initVersionsTab({
 
         const actionButton = event.target.closest('[data-version-action]');
         if (actionButton) {
+            // Check if browser extension has already handled this action
+            if (actionButton.dataset.lmExtensionHandled === 'true') {
+                return;
+            }
+            
             const row = actionButton.closest('.model-version-row');
             if (!row) {
                 return;
@@ -1190,6 +1195,11 @@ export function initVersionsTab({
         window.open(targetUrl, '_blank', 'noopener,noreferrer');
     });
 
+    // Listen for extension-triggered refresh requests
+    container.addEventListener('lm:refreshVersions', async () => {
+        await refresh();
+    });
+
     return {
         load: options => loadVersions(options),
         refresh,

static/js/managers/DownloadManager.js

@@ -744,3 +744,8 @@ export class DownloadManager {
 
 // Create global instance
 export const downloadManager = new DownloadManager();
+
+// Expose to window for browser extension integration
+if (typeof window !== 'undefined') {
+    window.downloadManager = downloadManager;
+}