security: fix auth bypass, XSS, IDOR, command injection, session hardening, rate limiting

- Phase 1: Require authentication for API register endpoint; restrict role creation
- Phase 2: Add $fillable whitelist to Server model to prevent mass assignment
- Phase 3: Fix XSS via escapeHtml in sidebar, JSON_HEX_TAG in script embeds
- Phase 4: Add canView() checks to TerminalController history/clearHistory
- Phase 5: escapeshellarg() on certbot params, sanitize service names, regex-based command blocklist, suppress exception messages
- Phase 6: SESSION_SECURE=true, SameSite=Strict, logout via POST+CSRF, chmod 640 .env
- Phase 7: DB-based rate limiting replacing session-based, applied to API login/register

views/layouts/main.php

@@ -132,7 +132,10 @@
                     </div>
                     <div class="user-menu">
                         <a href="/profile" title="Profile"><i class="fas fa-user-cog"></i></a>
-                        <a href="/logout" title="Logout"><i class="fas fa-sign-out-alt"></i></a>
+                        <form method="POST" action="/logout" class="logout-form" style="display:inline">
+                            <input type="hidden" name="_csrf_token" value="<?= $this->csrfToken() ?>">
+                            <button type="submit" title="Logout" style="background:none;border:none;color:inherit;cursor:pointer;padding:0;font:inherit;line-height:1"><i class="fas fa-sign-out-alt"></i></button>
+                        </form>
                     </div>
                 </div>
             </div>
@@ -407,7 +410,7 @@ function toggleServerList(e) {
                         const status = s.current_status === 'online' ? 'success' : s.current_status === 'offline' ? 'danger' : 'muted';
                         html += '<a href="/servers/' + s.id + '" class="nav-sub-item">'
                             + '<span class="status-dot-sm status-' + status + '"></span> '
-                            + s.name + '</a>';
+                            + escapeHtml(s.name) + '</a>';
                     });
                     sub.innerHTML = html;
                 } else {