Add stderr logging for Docker images command failure

Agent changes:
- Log stderr output when docker images command fails
- This will show the actual error message (e.g., permission denied, docker not found)
- Helps diagnose why docker images collection is failing

Updated to version 0.1.177

agent/src/collectors/systemd.rs

@@ -834,7 +834,8 @@ impl SystemdCollector {
         let output = match output {
             Ok(out) if out.status.success() => out,
             Ok(out) => {
-                info!("Docker images command failed with status: {}", out.status);
+                let stderr = String::from_utf8_lossy(&out.stderr);
+                info!("Docker images command failed with status: {}, stderr: {}", out.status, stderr);
                 return images;
             }
             Err(e) => {