fix(cron): clarify schedule and prompt requirements in parameter descriptions

[AgatheBauer]

This PR resolves the issue where description-driven models (e.g., Grok) omit the required schedule and prompt parameters when calling cronjob(action='create').

Since using the schema's root-level required array for this is not feasible (as it would reject non-create actions like list or remove if they omit schedule), this PR implements the maintainer-recommended targeted description update.

Changes:

• Prefixed the prompt parameter description with REQUIRED for action=create (unless no_agent=True or script is set).
• Clarified the schedule parameter description to explicitly start with REQUIRED for action=create. You MUST always include this parameter if action=create.
• Preserved clean Unix LF line endings to avoid CRLF diff noise.

[teknium1]

Thanks for the targeted schema clarification.

Automated hermes-sweeper review found that current main already implements and tests this description-driven fix:

• tools/cronjob_tools.py:994 explicitly states that schedule and prompt are required for action=create; tools/cronjob_tools.py:1006 independently marks schedule as required.
• Commit 51013268cf9b0ccc1078c8534cafef48eab145e7 introduced that guidance for description-driven models and is present in current main.
• tests/cron/test_cronjob_schema.py:12 covers the action and schedule description contract while retaining the action-only top-level required array.
• The proposed prompt exception for any supplied script would not match current validation: tools/cronjob_tools.py:693-706 still requires a prompt or skill for normal agent jobs; only no_agent=True changes that requirement.

Closing as implemented on main.