chore: CHANGELOG + tick M6.4 in progress tracker — SHA 689f1c0

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md

@@ -4,7 +4,7 @@ Companion to [2026-05-03-2349-go-backend-rewrite.md](2026-05-03-2349-go-backend-
 
 **Current milestone:** M6 — Go-native HTML frontend
 **Started:** 2026-05-04
-**Last updated:** 2026-05-08 (M6.2 merged)
+**Last updated:** 2026-05-08 (M6.4 merged)
 
 ## How to use
 
@@ -113,7 +113,7 @@ Goal: feature-equivalent UX on the Go side, designed cleanly. Not a Jinja port.
 - [x] **M6.1** Template skeleton: base layout, nav (Adults/Juniors/Payments/Sync/Flush), terminal-green-on-black theme; `embed.FS` for `templates/` + `static/` — `78e5059`
 - [x] **M6.2** `/adults` page: table, name filter input, month range filter, totals row, credits/debts/unmatched sections, Pay buttons that link to `/qr` — `c85748b`
 - [x] **M6.3** `/juniors` page: same structure + per-month J/A attendance breakdown + `"?"` sentinel rendering — `9564103`
-- [ ] **M6.4** `/payments` page: grouped-by-person ledger view
+- [x] **M6.4** `/payments` page: grouped-by-person ledger view — `689f1c0`
 - [ ] **M6.5** Modal JS module (`static/js/member-detail.js`): fetches `/api/adults` (or juniors), renders status/exceptions/transactions on row click; keyboard nav (Esc, ↑/↓)
 - [ ] **M6.6** `/qr`, `/sync-bank`, `/flush-cache`, `/version` pages
 - [ ] **M6.7** Wire `embed.FS` into handlers; verify single-binary deployment includes all assets