fix: friends tab navigation + full friends system upgrade

- Fix: clicking friends tab now always shows friends scene (not
  notifications). Tab click resets to root when already active.
- Friends list: sorted online-first, shows count, retry on error
- Pending requests: fetches requester profiles (name, avatar, level)
  instead of showing raw UUIDs
- Search: searches both username and display_name, debounced input
- Online tab: auto-refreshes every 15s
- Activity feed: timeAgo formatting, action icons
- API: added 'profiles' action for batch profile lookups, search
  now matches display_name too
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/friends.php

@@ -62,14 +62,25 @@ if ($method === 'GET') {
         if (strlen($query) < 2) jsonError('Query too short');
 
         $results = $db->get('profiles', [
-            'username' => 'ilike.*' . $query . '*',
+            'or' => "(username.ilike.*{$query}*,display_name.ilike.*{$query}*)",
             'id' => 'neq.' . $userId,
             'select' => 'id,username,display_name,avatar_url,level,is_online',
-            'limit' => 10
+            'limit' => 15
         ]);
 
         jsonResponse(['players' => is_array($results) && !isset($results['error']) ? $results : []]);
     }
+
+    if ($action === 'profiles') {
+        $ids = $_GET['ids'] ?? '';
+        if (!$ids) jsonResponse(['profiles' => []]);
+        $idList = implode(',', array_map('trim', explode(',', $ids)));
+        $profiles = $db->get('profiles', [
+            'id' => "in.({$idList})",
+            'select' => 'id,username,display_name,avatar_url,level,is_online'
+        ]);
+        jsonResponse(['profiles' => is_array($profiles) && !isset($profiles['error']) ? $profiles : []]);
+    }
 }
 
 if ($method === 'POST') {

public/js/core/hud.js

@@ -98,7 +98,8 @@ function renderTabBar() {
     const item = e.target.closest('.tab-item');
     if (!item) return;
     const world = item.dataset.world;
-    scene.switchWorld(world);
+    const isAlreadyActive = item.classList.contains('active');
+    scene.switchWorld(world, isAlreadyActive);
   });
 
   document.body.appendChild(tabBar);

public/js/core/scene.js

@@ -26,15 +26,19 @@ export function register(id, mountFn, unmountFn) {
   sceneRegistry[id] = { mount: mountFn, unmount: unmountFn };
 }
 
-export function switchWorld(world) {
-  if (!worlds.includes(world) || world === currentWorld) return;
+export function switchWorld(world, resetToRoot = false) {
+  if (!worlds.includes(world)) return;
+  if (world === currentWorld && !resetToRoot) return;
   const prev = currentWorld;
   currentWorld = world;
   store.set('activeWorld', world);
   bus.emit('world:changed', { from: prev, to: world });
 
   const stack = sceneStacks[world];
-  if (stack.length > 0) {
+  if (resetToRoot && stack.length > 1) {
+    sceneStacks[world] = [stack[0]];
+    renderScene(stack[0]);
+  } else if (stack.length > 0) {
     renderScene(stack[stack.length - 1]);
   }
 }