feat(ui): synthesis/superseded badges + merge provenance in lessons-tab (#162)

עוצב ואושר דרך שער-העיצוב (Claude Design 12c-training-lessons.html).
- lessons-tab: SOURCE_BADGE['synthesis']="סינתזה" (navy מלא) · REVIEW_BADGE['superseded']="מוזג"
  (אפור-מעומעם, לא נדחה); שורות superseded מעומעמות (opacity).
- provenance: לקח-על מציג "⤷ מוזג מ-N לקחים · דחייה תשחזר אותם".
- backend: list_decision_lessons + _lesson_to_json מחזירים synthesized_from; training.ts
  DecisionLesson — 'synthesis'/'superseded' ל-unions + synthesized_from?: string[].

הבאדג'ים היו מוגנים-fallback קודם (ללא קריסה) — כעת מתויגים נכון. closes #162.

בדיקות: py_compile ✓ · leak-guard ✓ · tsc --noEmit ✓.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web-ui/src/lib/api/training.ts

@@ -504,14 +504,20 @@ export type DecisionLesson = {
   category: "style" | "structure" | "lexicon" | "tabular" | "general";
   // "panel:deepseek+gemini" — the two-judge style panel; (string) keeps it open
   // to future panel sources without a type break.
-  source: "manual" | "curator" | "chair" | "style_analyzer" | (string & {});
+  // "synthesis" — a super-lesson merging overlapping lessons (#158/INV-LRN8);
+  // "panel:deepseek+gemini" — the two-judge style panel; (string) keeps it open.
+  source: "manual" | "curator" | "chair" | "style_analyzer" | "synthesis" | (string & {});
   // review gate (INV-LRN1/G10): only "approved" lessons flow to the writer.
   // Panel-written lessons start as "proposed" and wait for the chair here.
+  // "superseded" — a source lesson merged into a synthesis (#158); kept as
+  // provenance, no longer fed to the writer.
   // (applied_to_skill removed — LRN-1/INV-IA3: review_status is the single gate.)
-  review_status: "proposed" | "approved" | "rejected";
+  review_status: "proposed" | "approved" | "rejected" | "superseded";
   created_by: string;
   created_at: string;
   updated_at: string;
+  // #158/INV-LRN8: ids of the source lessons a 'synthesis' row merged (provenance).
+  synthesized_from?: string[];
 };
 
 export type LessonReviewStatus = DecisionLesson["review_status"];