Add per-embed lesson-type and section options to the booking block

Three sidebar options on the Lesson Booking block, all mirrored as shortcode
attributes and carried to the front end as data attributes on
#us-booking-app (or as omitted containers):

- Lesson type (lessonTypeId / lesson_type) pins the calendar to a single
  private-lesson type: only the times bookable as it are listed, and it is
  the only type bookable there, auto-selected on the registration form. A
  pinned type that is no longer offered says so instead of showing an empty
  calendar.
- Show the lesson-type filter (showTypeFilter / show_filter) drops the
  "Show Only" control for studios that do not want it.
- Sections (displayMode / show) embeds one half of the page — the booking
  calendar or the student's upcoming lessons — so the two can live on
  different pages. The script skips the work belonging to a missing half:
  no availability or catalog request for an upcoming-only embed, no
  bookings request for a booking-only one. An unrecognised value renders
  the whole page. The editor preview follows the same setting.

Also fixes the expanded filter's first lesson type sharing a line with the
"Lesson type" heading — the choices now sit in their own row beneath it.

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

docs/features/lesson-booking.md

@@ -58,6 +58,28 @@ instructor, the tied offering when there is one, otherwise a matching
 `duration_minutes`). The filter is a browsing aid only: the server re-checks
 every booking regardless.
 
+Two block/shortcode options change what the filter has to work with (see
+`editor-blocks.md`), passed to the script as data attributes on
+`#us-booking-app`:
+
+- **A pinned lesson type** (`data-lesson-type`) narrows the catalog to that one
+  offering, so the page lists only the times bookable as it and books nothing
+  else — the filter control hides itself, there being one type left. A pinned
+  type that is no longer offered shows "This lesson type is not available for
+  booking right now" rather than an empty calendar.
+- **Filter off** (`data-type-filter="0"`) drops the **Show Only** button
+  entirely; every open time is listed, as before the filter existed.
+
+## Embedding Halves of the Page
+The page has two halves — the booking calendar and the student's upcoming
+lessons — and the block/shortcode can embed either on its own (`displayMode` /
+`show`: `both` (default), `booking`, `upcoming`). The template simply omits the
+containers of the half that is not wanted, and the script skips the work that
+belongs to a missing container: an upcoming-only embed never requests
+availability or the offering catalog, and a booking-only embed never requests
+`GET /bookings`. An unrecognised value renders the whole page, so a typo cannot
+silently hide half of it.
+
 ## Cancellation
 Students cancel their own lessons via `POST /bookings/{id}/cancel` (idempotent).
 Cancelling marks the lesson `cancelled`, frees the availability slot for
@@ -120,7 +142,7 @@ acceptance time and IP), and their intake-question answers. On **My Lessons** an
 instructor may only open their own lessons; the studio **Scheduler** may open any.
 
 ## Frontend Shortcodes
-- `[us_booking]` — student calendar + registration flow; requires `book_lesson` capability
+- `[us_booking]` — student calendar + registration flow; requires `book_lesson` capability. Attributes: `login_page_id`, `lesson_type` (pin one private-lesson offering), `show_filter` (`no` hides the **Show Only** filter), `show` (`both` / `booking` / `upcoming`)
 - `[us_student_login]` — front-end login form for students
 
 ## Implementation