fix: 强化原子扣分账本 / enforce atomic deduction ledger

[yyuan308]

摘要 / Summary

• 强化 execution-contract 的 deduction trace 规则：每条 trace 必须引用 rubric 中的原子 criterion，并原样使用其声明分值；禁止拆分、缩放或为了凑总额虚构扣分。
• Strengthens execution-contract deduction traces: each trace must use an atomic declared criterion and its exact declared points; splitting, rescaling, and invented bookkeeping amounts are prohibited.
• 重试提示同步重复这条约束，帮助模型修复结构性 trace 错误，而不修改冻结 rubric、课程分值、gold 或 packet。
• The retry prompt repeats the same constraint to repair trace bookkeeping without changing the frozen rubric, course points, gold, or packets.

验证 / Verification

• python -m unittest tests.benchmark.core.test_model_runner — 22 passed
• python scripts/run_ci_tests.py core — 483 passed
• 已确认 Data/ 仍被 Git ignore；PR 仅包含公共 runner 与合成测试。

隐私、限制与下一步 / Privacy, limitations, and next step

• 未暂存或提交任何学生内容、成绩、转录、gold、运行输出或 Data/ 文件。
• No student content, scores, transcripts, gold, run outputs, or Data/ files are staged or committed.
• 本 PR 不报告任何模型指标或准确率结论。合并后将以同一冻结 G1 packet 启动全新的 DeepSeek 运行，残缺运行不会计入结果。