Improve error messages for script deployment failures

Show stdout, stderr, or exit code when deployment fails to help debug issues

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/monitors.py

@@ -283,17 +283,19 @@ class MonitorService:
             write_cmd = f"sudo tee {script_path} > /dev/null << 'KUMA_SCRIPT_EOF'\n{script_content}KUMA_SCRIPT_EOF"
             result = ssh.execute(hostname, write_cmd, username, port)
             if not result.success:
+                error_detail = result.stderr or result.stdout or f"exit code {result.exit_code}"
                 return {
                     "status": "failed",
-                    "error": f"Failed to write script: {result.stderr}",
+                    "error": f"Failed to write script: {error_detail}",
                 }
 
             # Make the script executable
             chmod_result = ssh.execute(hostname, f"sudo chmod +x {script_path}", username, port)
             if not chmod_result.success:
+                error_detail = chmod_result.stderr or chmod_result.stdout or f"exit code {chmod_result.exit_code}"
                 return {
                     "status": "failed",
-                    "error": f"Failed to make script executable: {chmod_result.stderr}",
+                    "error": f"Failed to make script executable: {error_detail}",
                 }
 
             # Add cronjob entry (remove existing entry first to avoid duplicates)