Fix all admin endpoint response formats

Wrap all admin endpoint responses in { data: ... } to match frontend
expectations and project conventions:
- PATCH /users/:id (enable/disable)
- PATCH /users/:id/role (promote/demote)
- GET /users/:id/activity
- GET /activity
- PATCH /settings

routes/admin.js

@@ -164,8 +164,10 @@ router.patch('/users/:id', async (req, res) => {
     });
 
     res.json({
-      user: updatedUser,
-      message: isActive ? 'User enabled successfully' : 'User disabled successfully'
+      data: {
+        user: updatedUser,
+        message: isActive ? 'User enabled successfully' : 'User disabled successfully'
+      }
     });
   } catch (error) {
     console.error('Error updating user status:', error);
@@ -249,8 +251,10 @@ router.patch('/users/:id/role', async (req, res) => {
       : 'User demoted to user successfully';
 
     res.json({
-      user: updatedUser,
-      message
+      data: {
+        user: updatedUser,
+        message
+      }
     });
   } catch (error) {
     console.error('Error updating user role:', error);
@@ -299,12 +303,14 @@ router.get('/users/:id/activity', async (req, res) => {
     ]);
 
     res.json({
-      activities,
-      pagination: {
-        page,
-        limit,
-        total,
-        pages: Math.ceil(total / limit) || 0
+      data: {
+        activities,
+        pagination: {
+          page,
+          limit,
+          total,
+          pages: Math.ceil(total / limit) || 0
+        }
       }
     });
   } catch (error) {
@@ -434,12 +440,14 @@ router.get('/activity', async (req, res) => {
     const activities = await collection.aggregate(pipeline).toArray();
 
     res.json({
-      activities,
-      pagination: {
-        page: validatedPage,
-        limit: validatedLimit,
-        total,
-        pages: Math.ceil(total / validatedLimit) || 0
+      data: {
+        activities,
+        pagination: {
+          page: validatedPage,
+          limit: validatedLimit,
+          total,
+          pages: Math.ceil(total / validatedLimit) || 0
+        }
       }
     });
   } catch (error) {
@@ -1123,8 +1131,10 @@ router.patch('/settings', async (req, res) => {
     const updatedSettings = await getSettings(db);
 
     res.json({
-      settings: updatedSettings,
-      message: 'Settings updated successfully'
+      data: {
+        settings: updatedSettings,
+        message: 'Settings updated successfully'
+      }
     });
   } catch (error) {
     console.error('Error updating settings:', error);