1aa250ca67
History was logging every article merely displayed, which made it noise. Split
the two concepts cleanly:
- "displayed" (seenIds) still tracks everything shown, but only to stop Replace
recycling stories — it no longer feeds history.
- "history" now records only deliberate events: articles the user OPENED (card
click) or ones they REPLACED away (recoverable accidental swaps).
Also: per-item removal (× in the History panel; DELETE /api/history/{id}), and
when signed in the panel shows the account (cross-device) history. First-sign-in
import now folds the meaningful history (not everything shown). Copy updated.
115 tests pass.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>