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/editor-blocks.md

@@ -27,6 +27,9 @@ Four blocks have sidebar (inspector) options:
 |---|---|---|---|
 | `us-scheduler/booking` | `loginPageId` (number) | `0` | Page the "log in to book a lesson" link points to for logged-out visitors. `0` = the WordPress login screen (with a redirect back to the current page). |
 | `us-scheduler/booking` | `autoRedirect` (boolean) | `false` | Send logged-out visitors straight to the login page instead of showing the link. |
+| `us-scheduler/booking` | `lessonTypeId` (number) | `0` | Pin the calendar to a single private-lesson type: only the times bookable as that type are listed, and it is the only type students can book here (auto-selected on the registration form). `0` = every type. Shortcode equivalent: `[us_booking lesson_type="…"]`. |
+| `us-scheduler/booking` | `showTypeFilter` (boolean) | `true` | Whether students get the **Show Only** button that narrows the calendar to chosen lesson types. Unused when a single type is pinned (there is nothing to choose). Shortcode equivalent: `[us_booking show_filter="no"]`. |
+| `us-scheduler/booking` | `displayMode` (string) | `both` | Which halves of the page to embed: `both`, `booking` (calendar only, no upcoming-lessons panel) or `upcoming` (the student's lessons only, nothing bookable) — so the two halves can live on different pages. Anything unrecognised falls back to `both`. Shortcode equivalent: `[us_booking show="booking"]`. |
 | `us-scheduler/student-login` | `bookingPageId` (number) | `0` | Page the "View available lessons" link points to for logged-in visitors, and the post-login redirect target. `0` = the current page. |
 | `us-scheduler/student-login` | `autoRedirect` (boolean) | `false` | Send logged-in visitors straight to the booking page instead of showing the link. Does nothing until a booking page is chosen. |
 | `us-scheduler/student-register` | `loginPageId` (number) | `0` | Page students continue to once registration finishes — the "Sign in to your account" link after they confirm their email, and the "Continue to your account" link an invited student gets on the spot. `0` = the WordPress login screen for the confirmation link, and no link at all for the (already signed-in) invited student. Shortcode equivalent: `[us_student_register login_page_id="…"]`. |
@@ -38,7 +41,15 @@ the blocks fall back to their defaults. The group-classes block's class
 select is a dropdown of active group classes fetched from
 `GET /us-scheduler/v1/offerings?kind=group_class`; a stored class that is no
 longer offered shows as "Unavailable class #N" rather than silently falling
-back to all classes. The link targets are also available
+back to all classes. The booking block's lesson-type select works the same way
+against `?kind=private_lesson` ("Unavailable lesson type #N"), and the live
+page says so plainly when the pinned type has been withdrawn.
+
+The booking block's options reach the front end as data attributes on
+`#us-booking-app` (`data-lesson-type`, `data-type-filter`) or as omitted
+containers (`displayMode`), which `assets/js/booking.js` reads on load — see
+`lesson-booking.md`. Its editor preview follows `displayMode`, showing the
+calendar, the upcoming-lessons panel, or both. The link targets are also available
 to the shortcodes as `[us_booking login_page_id="…"]` and
 `[us_student_login booking_page_id="…"]`; auto-redirect is block-only.