Extend availability (durations, weekly recurrence, calendar); price offerings in dollars

Availability (#2):
- us_availability gains offering_id, duration_minutes (default 60), and
  recurrence_group; AvailabilitySlot carries the new fields.
- AvailabilityRepository::createWeeklySeries() generates N weekly rows
  sharing a recurrence_group; findAvailable() filters by offering and
  duration. Date math uses DateTimeImmutable::modify() (the no-debug CI
  regex `dd\(` matches `->add(`).
- REST GET filters by offering_id/duration_minutes; POST accepts
  duration_minutes, offering_id, recurrence (single|weekly) + weeks.
- Admin form adds duration, an offering picker, and one-off/weekly options
  (OfferingRepository wired into AvailabilityController).
- booking.js renders an agenda calendar (slots grouped by day, with
  duration). The richer booking UX lands with the booking-flow work.

Offering price in dollars:
- Switch us_offerings.price_cents (INT) to price DECIMAL(10,2); Offering
  uses float $price. Admin form and REST take dollars.
- Fix a pre-existing misalignment in the Offering insert/update $wpdb
  format arrays (billing_mode/capacity/is_active were mapped to the wrong
  specifiers, which would corrupt values) via a single COLUMN_FORMATS list.

Also bump PHPStan to --memory-limit=1G in the lint script; 128M now
crashes analysis as the codebase has grown.

Refs #2

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/Availability/AvailabilitySlot.php

@@ -9,17 +9,23 @@ class AvailabilitySlot {
 		public readonly int $instructorId,
 		public readonly string $startDt,
 		public readonly string $endDt,
+		public readonly int $durationMinutes = 60,
+		public readonly ?int $offeringId = null,
 		public readonly bool $isBooked = false,
+		public readonly ?int $recurrenceGroup = null,
 		public readonly ?int $id = null,
 	) {}
 
 	public static function fromRow( object $row ): self {
 		return new self(
-			instructorId: (int) $row->instructor_id,
-			startDt:      $row->start_dt,
-			endDt:        $row->end_dt,
-			isBooked:     (bool) $row->is_booked,
-			id:           (int) $row->id,
+			instructorId:    (int) $row->instructor_id,
+			startDt:         $row->start_dt,
+			endDt:           $row->end_dt,
+			durationMinutes: (int) $row->duration_minutes,
+			offeringId:      null !== $row->offering_id ? (int) $row->offering_id : null,
+			isBooked:        (bool) $row->is_booked,
+			recurrenceGroup: null !== $row->recurrence_group ? (int) $row->recurrence_group : null,
+			id:              (int) $row->id,
 		);
 	}
 
@@ -30,11 +36,14 @@ class AvailabilitySlot {
 	 */
 	public function toArray(): array {
 		return [
-			'id'            => $this->id,
-			'instructor_id' => $this->instructorId,
-			'start_dt'      => $this->startDt,
-			'end_dt'        => $this->endDt,
-			'is_booked'     => $this->isBooked,
+			'id'               => $this->id,
+			'instructor_id'    => $this->instructorId,
+			'offering_id'      => $this->offeringId,
+			'start_dt'         => $this->startDt,
+			'end_dt'           => $this->endDt,
+			'duration_minutes' => $this->durationMinutes,
+			'is_booked'        => $this->isBooked,
+			'recurrence_group' => $this->recurrenceGroup,
 		];
 	}
 }