fix: add sudo fallback to agent installer + improve error output

- AgentService: try sudo -n first, fall back to bash without sudo
- AgentService: add sudo to uninstall command
- AgentService: trim error output to last 20 lines for readability
- View: show SSH output inline in error toast
- Fix undefined $path variable in success path

src/Services/AgentService.php

@@ -49,9 +49,12 @@ class AgentService
 
         $script = file_get_contents($scriptPath);
 
+        $b64 = base64_encode($script);
         $remoteCommand = sprintf(
-            'echo %s | base64 -d | bash -s -- %s %s 2>&1',
-            escapeshellarg(base64_encode($script)),
+            'echo %s | base64 -d | (sudo -n true 2>/dev/null && sudo bash -s -- %s %s || bash -s -- %s %s) 2>&1',
+            escapeshellarg($b64),
+            escapeshellarg($serverUrl),
+            escapeshellarg($agentKey),
             escapeshellarg($serverUrl),
             escapeshellarg($agentKey)
         );
@@ -67,17 +70,17 @@ class AgentService
 
             $output = trim($result['output']);
             $exitStatus = $result['exit_status'] ?? -1;
+            $path = '/usr/local/bin/servermanager-agent';
 
             if ($exitStatus !== 0) {
+                $lastLines = implode("\n", array_slice(explode("\n", $output), -20));
                 return [
                     'success' => false,
                     'error' => 'Agent installation failed on remote server',
-                    'output' => $output,
+                    'output' => $lastLines,
                 ];
             }
 
-            $path = '/usr/local/bin/servermanager-agent';
-
             $serverModel = new \ServerManager\Models\Server();
             $serverModel->setAgentInstalled($serverId, true, $path);
 
@@ -116,7 +119,7 @@ class AgentService
         $script = file_get_contents($scriptPath);
 
         $remoteCommand = sprintf(
-            'echo %s | base64 -d | bash 2>&1',
+            'echo %s | base64 -d | sudo bash 2>&1',
             escapeshellarg(base64_encode($script))
         );