feat: admin users can view all downloads with user badges

- Admin users (Emby IsAdministrator) see a 'Show all users' toggle
- When toggled, all tagged downloads are shown regardless of user
- Each download card shows the tagged user's name as a badge
- Non-admin users see only their own downloads (unchanged behavior)
- Backend accepts ?showAll=true query param (admin-only)

server/routes/auth.js

@@ -37,9 +37,11 @@ router.post('/login', async (req, res) => {
     console.log(`[Auth] Login successful for user: ${user.Name}`);
     
     // Set authentication cookie
+    const isAdmin = !!(user.Policy && user.Policy.IsAdministrator);
     res.cookie('emby_user', JSON.stringify({
       id: user.Id,
       name: user.Name,
+      isAdmin: isAdmin,
       token: authData.AccessToken
     }), {
       httpOnly: true,
@@ -50,7 +52,8 @@ router.post('/login', async (req, res) => {
       success: true,
       user: {
         id: user.Id,
-        name: user.Name
+        name: user.Name,
+        isAdmin: isAdmin
       }
     });
   } catch (error) {
@@ -76,7 +79,8 @@ router.get('/me', (req, res) => {
       authenticated: true,
       user: {
         id: user.id,
-        name: user.name
+        name: user.name,
+        isAdmin: !!user.isAdmin
       }
     });
   } catch (error) {