Let the studio book lessons and record intake collected elsewhere

Two related gaps, closed together because the second is created by the first.

A private lesson could only be booked by the student or their guardian, so a
booking taken over the phone had no way in — where group classes have had "Add
students directly" all along. "Book a lesson for a student" is now a panel on
Scheduler and My Lessons: student, open time, lesson type, with weekly term
reservations and a no-charge option for make-up lessons. The booking core is
extracted to Booking\LessonBooker and shared with POST /bookings, so the two
paths cannot drift on offering rules, slot claiming, or billing.

That leaves a registration with no intake answers and no policy acceptances,
because nobody was at a keyboard to give them — already true of every directly
added group-class student. Ticking the boxes on a student's behalf would be an
audit trail that says something untrue, so instead the answers are collected
another way and recorded afterwards, from a lesson's or an enrolment's detail
page. Every recording must say how it was collected, which is stamped on each
row along with who typed it and shown in a new "How it was given" column: a
policy ticked online and one transcribed from paper must never look alike.

Only staff-made registrations qualify (us_lessons.booked_by,
us_group_enrollments.enrolled_by) — one the student made already holds their
own answers. Only what is still missing can be recorded, re-checked at write
time, so a stale or double-posted form cannot duplicate or overwrite. No IP is
stored for a transcription, and accepted_by stays the student while recorded_by
names the staff member.

Intake is now generic over Registration\IntakeSubject, which Lesson and
Enrollment both implement; LessonDetail became Registration\IntakeAudit and is
shared by both detail views rather than duplicated.

Closes #182

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01QfHt6CyJHz6KkA4RuaS7WK

src/Booking/Lesson.php

@@ -3,9 +3,11 @@ declare(strict_types=1);
 
 namespace Unsupervised\Schedular\Booking;
 
+use Unsupervised\Schedular\Registration\Answer;
+use Unsupervised\Schedular\Registration\IntakeSubject;
 use Unsupervised\Schedular\Val;
 
-class Lesson {
+class Lesson implements IntakeSubject {
 
 	public const STATUS_PENDING   = 'pending';
 	public const STATUS_CONFIRMED = 'confirmed';
@@ -38,9 +40,47 @@ class Lesson {
 		public readonly string $status = self::STATUS_PENDING,
 		public readonly ?int $paymentId = null,
 		public readonly ?string $notes = null,
+		/**
+		 * The staff member who booked this lesson on the student's behalf, from
+		 * wp-admin; 0 when it was booked through the student-facing flow, by the
+		 * student or their guardian. It is what marks a lesson whose intake answers
+		 * and policy acceptances may be recorded after the fact — nobody was at a
+		 * keyboard to give them at booking time.
+		 */
+		public readonly int $bookedBy = 0,
 		public readonly ?int $id = null,
 	) {}
 
+	public function intakeRegistrationType(): string {
+		return Answer::REG_LESSON;
+	}
+
+	/**
+	 * The lesson id this booking's intake answers and policy acceptances hang
+	 * off: the series anchor for a weekly reservation, the lesson itself
+	 * otherwise. A series is answered for and agreed to once, so every occurrence
+	 * reads and writes the same registration.
+	 */
+	public function intakeRegistrationId(): int {
+		return $this->seriesId ?? (int) $this->id;
+	}
+
+	public function intakeOfferingId(): int {
+		return (int) $this->offeringId;
+	}
+
+	public function intakeStudentId(): int {
+		return $this->studentId;
+	}
+
+	/**
+	 * Whether the studio booked this lesson on the student's behalf, rather than
+	 * the student (or their guardian) booking it themselves.
+	 */
+	public function isStaffRegistered(): bool {
+		return $this->bookedBy > 0;
+	}
+
 	public static function fromRow( \stdClass $row ): self {
 		return new self(
 			slotId:       Val::int( $row->slot_id ),
@@ -52,6 +92,7 @@ class Lesson {
 			status:       Val::string( $row->status ),
 			paymentId:    Val::intOrNull( $row->payment_id ),
 			notes:        Val::stringOrNull( $row->notes ),
+			bookedBy:     Val::int( $row->booked_by ?? 0 ),
 			id:           Val::int( $row->id ),
 		);
 	}
@@ -73,6 +114,7 @@ class Lesson {
 			'status'        => $this->status,
 			'payment_id'    => $this->paymentId,
 			'notes'         => $this->notes,
+			'booked_by'     => $this->bookedBy,
 		];
 	}
 }