test(cli): cover stdin marker before options

[aiirvizionz]

Summary

• add regression coverage for the documented run - stdin marker when followed by --dry-run
• preserve the existing stdin coverage and option-validation behavior

The parser fix is already present on current upstream main; this PR contributes the missing regression test rather than duplicating that implementation.

Verification

• node --test --test-name-pattern="run - reads the script from stdin|run accepts - before --dry-run" test/run-options.test.mjs (2 passing)
• git diff --check
• full suite: 164 passing, with five pre-existing Windows/POSIX sandbox failures unrelated to this test

Please merge if this test-only coverage is useful; I will invoice only after merge.

[aiirvizionz]

Ready for review. The upstream parser fix is already present; this PR contributes the missing regression coverage for the documented stdin marker before --dry-run. Directed tests pass and the PR records the pre-existing full-suite environment failures. I will invoice only after merge under the accepted task.