shell: always print exit code, even on success

Ensures tool output is never blank - at minimum shows 'exit: 0'.

data/tools/shell

@@ -30,4 +30,10 @@ fi
 
 # Execute the command. The sandbox (landlock) is already applied by toolsrv.
 # We use eval to handle pipes, redirects, and compound commands.
-eval "$cmd"
+# Capture output and exit code, always report both.
+output=$(eval "$cmd" 2>&1) && rc=$? || rc=$?
+if [ -n "$output" ]; then
+  printf '%s\n' "$output"
+fi
+echo "exit: $rc"
+exit $rc