- Add outputs/prompts/article-summary-prompt.txt with deep knowledge
note schema (core_conclusion, main_argument, key_methods, etc.)
- Add ArticleSummaryResult Pydantic model for the new schema
- Add validate_article_summary_payload() validator
- Add optional validator param to run_loop_payload(); defaults to
existing validate_llm_result_payload so daily digest is unaffected
- Update article_summary.py: new prompt path, new validator, new
Markdown output with Chinese section headers
