Add server ownership, team access, role-based UI, and default admin role

- New migration 002_server_access.sql: created_by column + server_user table
- Server model: ownership, permission checks, team management methods
- Routes: /team routes, RoleMiddleware on /servers/create and /admin
- ServerController: permission checks via server_user, team CRUD methods
- TerminalController: server access checks
- DashboardController: filter servers by accessible ones
- ApiController: server access checks
- Views: team.php, team_server.php, sidebar Team link, hide actions by role
- Default user role changed from operator to admin on registration
- Admin user form defaults to admin role

views/admin/users.php

@@ -100,8 +100,8 @@
                     <div class="form-group">
                         <label for="modalRole">Role</label>
                         <select id="modalRole" name="role" class="form-select" required>
+                            <option value="admin" selected>Administrator</option>
                             <option value="operator">Operator</option>
-                            <option value="admin">Administrator</option>
                             <option value="super_admin">Super Administrator</option>
                         </select>
                     </div>
@@ -130,7 +130,7 @@ function showCreateUserModal() {
     document.getElementById('modalPassword').value = '';
     document.getElementById('modalPassword').required = true;
     document.getElementById('passwordHint').style.display = 'block';
-    document.getElementById('modalRole').value = 'operator';
+    document.getElementById('modalRole').value = 'admin';
     document.getElementById('modalActive').checked = true;
     document.getElementById('saveUserBtn').textContent = 'Create';
     document.getElementById('userModal').style.display = 'flex';