style_lesson_panel.py: before writing 2/2-keep lessons, skip any whose normalized
lesson_text already exists on the corpus (any source), and collapse duplicates within
a run. Makes the run-learning button safe to click repeatedly (the curator may re-run
the pipeline) — it converges instead of piling up duplicate decision_lessons.
Verified on בל"מ 8126-03-25: re-running --apply with 7 existing lessons wrote 0
("1 כפילויות דולגו"), count stayed 7.
Invariants: INV-LRN1/G10 unchanged (proposals only, manual fold).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
