Replace old team system with work teams (equipos de trabajo)

- New migration 003_teams.sql: teams, team_user, team_server tables
- New Team model with CRUD, members, and server assignment
- New TeamController with full team management
- New views: teams/index, teams/create, teams/show
- Server model: getUserRole and getAccessibleServerIds now include team-based access
- Sidebar: Teams link under Administration (admin+ only)
- Routes: old /team routes removed, new /teams routes added
- Removed old ServerController team methods and views
- Fixed sidebar empty accessible IDs returning all servers
- Fixed dashboard and API to show empty when no accessible servers

src/Controllers/ApiController.php

@@ -77,9 +77,7 @@ class ApiController
         if ($search) $filters['search'] = $search;
 
         $accessibleIds = $serverModel->getAccessibleServerIds((int) $user['id']);
-        if (!empty($accessibleIds)) {
-            $filters['accessible_ids'] = $accessibleIds;
-        }
+        $filters['accessible_ids'] = !empty($accessibleIds) ? $accessibleIds : [-1];
 
         $servers = $serverModel->getAll($page, $perPage, $filters);