Makes the repo fully bilingual: every _en.md now has a matching _zh.md
sibling with identical section structure.
New translations:
- primers/technical_newsvendor_zh.md
- primers/technical_scuc_sced_zh.md
- primers/technical_stochastic_optimization_zh.md
- markets/us/field_guide_zh.md
- markets/us/forecasting_open_ecosystem_zh.md
README: link the new _zh docs and drop the "EN only" / awaiting-translation
markers. Translations follow house conventions (CJK bold padding, arabic
section-number parity, shared bilingual glossary, _zh cross-doc links).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
