fix(cron): pass shell scripts to bash with forward slashes

[bigleaguer]

Summary

• Pass .sh and .bash cron script paths to bash with forward slashes.
• Keep Python script execution unchanged.
• Add regression coverage for Windows-style script paths.

Fixes #43073

Tests

• .\.venv\Scripts\python.exe -m pytest tests/cron/test_cron_script.py --timeout-method=thread
• .\.venv\Scripts\python.exe -m pytest tests/tools/test_windows_native_support.py::TestCronSchedulerBashResolution --timeout-method=thread
• .\.venv\Scripts\python.exe -m ruff check cron/scheduler.py tests/cron/test_cron_script.py

[alt-glitch]

This was generated by AI during triage.

Duplicate of #43076 — both fix the same cron scheduler bug (#43073): bash .sh/.bash script paths mangled by backslashes on native Windows, fixed by passing forward/POSIX-style paths while leaving Python script execution unchanged. #43076 arrived first. Also part of the long-standing cluster #23404 / #23405 / #23489. Maintainer to pick the canonical fix.

[bigleaguer]

Closing this since #43076 already covers the same fix and was opened first. Thanks for checking.