Simplify self-service payments to full-amount checkout, add manual-page payment tab

Self-service "pay now" flows (registration success + user dashboard) now go
straight to a Yoco checkout for the full outstanding balance instead of
prompting for a partial amount; that page has been removed. Partial-amount
payment links remain supervisor/admin-only via the Payments dashboard.

Also adds a "Record Payment" tab to the supervisor manual registration page,
pre-filled with the most recently created registration, so staff can capture
a payment right after registering someone without leaving the page.

CHANGELOG.md

@@ -7,6 +7,18 @@ and this project follows [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+- Supervisor dashboard: `/dashboard/supervisor/manual` now has a "Record Payment" tab (alongside "Register"), for capturing a payment without leaving the page. It pre-fills with the user and registration from the most recently created manual registration, but only switches tabs when a supervisor/admin clicks it themselves.
+
+### Changed
+
+- Self-service payments ("Pay with Yoco" after registering, and "Make payment" on the user dashboard) now go straight to a Yoco checkout for the full remaining outstanding balance, instead of first showing a page to choose a custom/partial amount. Generating a partial-amount payment link remains available only from the supervisor/admin Payments dashboard.
+
+### Removed
+
+- `/dashboard/user/pay` — the self-service partial-payment page — has been removed; it's no longer linked to from anywhere in the app.
+
 ## [1.1.0] - 2026-07-24
 
 ### Added