feat(social): full friends system — search, add, pending requests, online filter, remove

Friends scene rebuilt:
- 3 tabs: الأصدقاء (all), الطلبات (pending), متصلين (online)
- Search players by username (🔍 button → input + results)
- Send friend request with + button (success feedback)
- Accept/reject pending requests (✓/✕ buttons)
- Remove friend (with confirm dialog)
- Challenge online friend (⚔️ → navigates to game select)
- View profile button
- Online dot indicator on avatars
- Empty states with helpful CTAs

API updated:
- New action: search — finds players by username (ilike)
- Returns id, username, display_name, avatar_url, level, is_online

UI polish:
- Tab system with active state
- Card-based friend list with actions
- Animations and haptic on interactions
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/friends.php

@@ -56,6 +56,20 @@ if ($method === 'GET') {
         ]);
         jsonResponse(['pending' => $pending ?: []]);
     }
+
+    if ($action === 'search') {
+        $query = $_GET['query'] ?? '';
+        if (strlen($query) < 2) jsonError('Query too short');
+
+        $results = $db->get('profiles', [
+            'username' => 'ilike.*' . $query . '*',
+            'id' => 'neq.' . $userId,
+            'select' => 'id,username,display_name,avatar_url,level,is_online',
+            'limit' => 10
+        ]);
+
+        jsonResponse(['players' => is_array($results) && !isset($results['error']) ? $results : []]);
+    }
 }
 
 if ($method === 'POST') {