feat: 诊断（任务书 18 第一块）：诊断数学、四种提交、一次运行跑多个实验、账本与材料、flow 诊断各步

消融默认关，关掉时解释阶段一并跳过；选诊断实验用信息价值减成本。
eval/diagnosis/research.json 为第三块配置。vocab 字段说明的出口文字随提示词一起改，见下一次提交的 prompts/ 与同文件改动（本次含在内）。

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/tasks/index.ts

@@ -2,14 +2,29 @@
 // 不起子进程：要执行任务代码的事都只交出运行定义，由调用方交给 runner 在任务镜像里跑。
 export { checkTaskFacts, TASK_KINDS, TaskFacts, type TaskKind } from "./facts.ts";
 export {
+  diagnosisRun,
+  diagnosisUnversionedNames,
   formalRun,
   judge,
+  judgeDiagnosis,
   lightCheck,
   loadTask,
   metricDefinitions,
+  placeBaselineArtifact,
+  prepareDiagnosisJudging,
+  prepareDiagnosisRun,
   prepareJudging,
   prepareRun,
   protectedChanges,
   readLightCheck,
 } from "./task.ts";
-export type { JudgingStep, LightCheckOutcome, Task } from "./types.ts";
+export type {
+  DiagnosisEnding,
+  DiagnosisExperiment,
+  DiagnosisExperimentJudged,
+  DiagnosisJudged,
+  DiagnosisJudgingStep,
+  JudgingStep,
+  LightCheckOutcome,
+  Task,
+} from "./types.ts";