fix(cron): accept UTF-8 BOM job stores

[HengYangDS]

Summary

Fixes #66607: a UTF-8 BOM at the start of ~/.hermes/cron/jobs.json no longer prevents the cron store, hermes dump, or hermes status from reading scheduled jobs.

All four jobs-store reads now use utf-8-sig; writes remain plain UTF-8, so the next successful write naturally produces a BOM-free file.

Validation

• python -m pytest tests/cron/test_jobs.py::TestJobCRUD::test_load_jobs_reads_utf8_bom_store tests/hermes_cli/test_dump_env_visibility.py tests/hermes_cli/test_status.py tests/hermes_cli/test_cron.py -q — 39 passed
• ruff check on the changed files — passed
• scripts/check-windows-footguns.py on the changed files — passed
• git diff --check — passed
• Runtime probe with a BOM-prefixed jobs.json: load_jobs(), dump summary, and status all reported one active job.

[HengYangDS]

Duplicate of #66609, which already contains the same four utf-8-sig reader changes and broader BOM coverage. Closing this duplicate to keep review and CI on the established PR.

[tonydwb]

Reviewed by Hermes Agent