Follow-up to the salvaged #110940 commit:
- `cron/scheduler_prompt.py::_CRON_HINT` tells the model the sentinel is a literal
ASCII control token that must never be translated or rephrased — the prompt-side
half of the fix, so a lane answering in any other language is steered to the
canonical token instead of relying on the filter knowing that language.
- Docs: the supported-token list ('Intentional Silence Tokens') gains the zh-Hans
forms in the English page and the zh-Hans mirror gets the section it lacked.
- Tests trimmed to two invariants (translated forms match in every shape the English
ones do; prose that mentions the word is still delivered), proven red on origin/main.