doc(test-cli): note that CI prints the resolved pytest command

Add a "Debugging CI Failures" subsection to `docs/dev/test_actions_locally.md`
pointing readers at the `Executing: pytest ...` line printed when `CI` is
set, so failing Github Actions jobs can be reproduced locally without
`gh act`.

Author: danceratopz

docs/dev/test_actions_locally.md

@@ -111,3 +111,13 @@ It's possible to specify the Docker image used by the `act` tool for a specific
 ```
 
 This can be added to any `gh act` command.
+
+## Debugging CI Failures
+
+The pytest-based CLIs (`fill`, `execute`, ...) print the resolved `pytest ...` invocation at startup whenever the `CI` environment variable is set:
+
+```text
+Executing: pytest ...
+```
+
+Copy this line verbatim from the failing Github Actions log and run it locally to reproduce the exact command, including all plugin and marker arguments injected by the CLI.