chore: tick M2.10 in progress tracker + CHANGELOG entry

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,10 @@
 - `scripts/infer_payments.py`: union adults + junior rosters so junior-only members are visible to the matcher.
 - Root cause: `get_members_with_fees()` reads only the adults sheet; junior-only kids like Jáchym Kubík were absent from `member_names`, causing the exact-match short-circuit to never fire and a different adult sharing the first name to win via fuzzy review.
 - Two regression tests added to `tests/test_match_members.py`.
+## 2026-05-06 16:05 CEST — feat(go/M2.10): port domain/reconcile.Reconcile
+
+- New `go/internal/domain/reconcile` package porting the three-phase payment allocation from `scripts/match_payments.py reconcile()`.
+- 12 unit tests covering all Python test cases plus Go-only extras (diacritics tolerance, `[?]` stripping, `other:` purpose, out-of-window credit, inference fallback, unmatched, no-transaction guard).
 
 ## 2026-05-06 13:18 CEST — feat(go/M2.7-2.9): port domain/matching package