Charge weekly reservations for every claimed occurrence and confirm the whole series

A weekly booking on a per-lesson (one_time) priced offering was creating its
single upfront payment for one week's price while reserving up to 12 weeks,
and settling that payment confirmed only the anchor lesson, leaving the rest
of the series pending forever.

- BookingEndpoint now charges price x claimed occurrences for one_time
  billing; a full_term price is still charged once since it covers the term.
- PaymentService::confirmRegistration resolves the anchor lesson's series and
  confirms every non-cancelled row via the new
  BookingRepository::updateStatusForSeries().

Closes #79

Co-Authored-By: Claude Fable 5 <[email protected]>

docs/features/lesson-booking.md

@@ -44,8 +44,13 @@ slot_taken` if the freed time was booked by someone else in the meantime.
 ## Weekly Reservations
 A weekly reservation creates one `series_id` shared across N lesson rows (one per
 week in the term) and reserves the matching availability windows. It is billed
-**full-term upfront** as a single payment (`billing_mode = full_term` on the
-offering).
+**upfront as a single payment** linked to the series' first (anchor) lesson:
+- `billing_mode = full_term` — the offering's price already covers the term and is charged once.
+- `billing_mode = one_time` — the per-lesson price is charged **once per occurrence actually claimed** (price × N).
+
+Settling that payment (Stripe webhook, e-transfer confirmation, comp) confirms
+**every non-cancelled lesson in the series**
+(`BookingRepository::updateStatusForSeries()`), not just the anchor row.
 
 ## REST API
 | Method    | Endpoint                                        | Permission                     |

docs/features/payments.md

@@ -6,7 +6,9 @@ falls back to **e-transfer** — a pending payment a studio admin marks received
 so everything works without any credentials. When Stripe **is** configured the
 default rail becomes the **credit card**. The studio admin can override any
 student's method (card / e-transfer / comp). Single bookings are charged once;
-weekly reservations and group classes are charged the full term upfront. A
+weekly reservations and group classes are charged the full term upfront (a
+`full_term` price once, or a per-lesson `one_time` price × the occurrences
+reserved — see `lesson-booking.md`). A
 numbered receipt is emailed automatically when a payment is marked paid.
 
 > **Implemented:** the payment ledger, studio settings, method resolution