fix: resolve P3 audit findings

src/components/AddDownloadsModal.tsx

@@ -531,7 +531,7 @@ export const AddDownloadsModal = () => {
                  let newName = finalFile;
                  let exists = true;
                  
-                 while (exists) {
+                 while (exists && count < 1000) {
                      newName = `${base} (${count})${ext}`;
                      const storeHas = useDownloadStore.getState().downloads.some(d => {
                          const dest = d.destination || useSettingsStore.getState().defaultDownloadPath || '~/Downloads';

src/components/DownloadTable.tsx

@@ -57,7 +57,8 @@ export const DownloadTable: React.FC<DownloadTableProps> = ({ filter }) => {
     } else if (dir === '~') {
       resolvedDir = await homeDir();
     }
-    return resolvedDir + '/' + file;
+    const separator = resolvedDir.endsWith('/') ? '' : '/';
+    return resolvedDir + separator + file;
   };
 
   const filteredDownloads = downloads.filter((d: DownloadItem) => {

src/components/Sidebar.tsx

@@ -247,7 +247,10 @@ export const Sidebar: React.FC<SidebarProps> = (props) => {
       {contextMenu && (
         <div
           className="fixed z-50 w-48 py-1 rounded-xl shadow-lg border border-border-modal bg-bg-context-menu backdrop-blur-xl animate-fade-in text-[13px] text-text-primary overflow-hidden"
-          style={{ top: contextMenu.y, left: contextMenu.x }}
+          style={{ 
+            top: Math.min(contextMenu.y, window.innerHeight - 200), 
+            left: Math.min(contextMenu.x, window.innerWidth - 200) 
+          }}
           onClick={e => e.stopPropagation()}
         >
           <button