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 <noreply@anthropic.com>

tests/Unit/Availability/AvailabilitySlotTest.php

@@ -11,58 +11,66 @@ class AvailabilitySlotTest extends TestCase
     public function testConstructorAndProperties(): void
     {
         $slot = new AvailabilitySlot(
-            instructorId: 5,
-            startDt:      '2026-04-01 09:00:00',
-            endDt:        '2026-04-01 10:00:00',
-            isBooked:     false,
-            id:           42,
+            instructorId:    5,
+            startDt:         '2026-04-01 09:00:00',
+            endDt:           '2026-04-01 10:00:00',
+            durationMinutes: 30,
+            offeringId:      8,
+            isBooked:        false,
+            recurrenceGroup: 100,
+            id:              42,
         );
 
         self::assertSame(5, $slot->instructorId);
         self::assertSame('2026-04-01 09:00:00', $slot->startDt);
-        self::assertSame('2026-04-01 10:00:00', $slot->endDt);
+        self::assertSame(30, $slot->durationMinutes);
+        self::assertSame(8, $slot->offeringId);
+        self::assertSame(100, $slot->recurrenceGroup);
         self::assertFalse($slot->isBooked);
         self::assertSame(42, $slot->id);
     }
 
-    public function testFromRowMapsCorrectly(): void
+    public function testDefaults(): void
+    {
+        $slot = new AvailabilitySlot(1, '2026-04-01 09:00:00', '2026-04-01 10:00:00');
+
+        self::assertSame(60, $slot->durationMinutes);
+        self::assertNull($slot->offeringId);
+        self::assertFalse($slot->isBooked);
+        self::assertNull($slot->recurrenceGroup);
+        self::assertNull($slot->id);
+    }
+
+    public function testFromRowMapsCorrectlyAndCastsNullables(): void
     {
         $row = (object) [
-            'id'            => '7',
-            'instructor_id' => '3',
-            'start_dt'      => '2026-05-10 14:00:00',
-            'end_dt'        => '2026-05-10 15:00:00',
-            'is_booked'     => '1',
+            'id'               => '7',
+            'instructor_id'    => '3',
+            'offering_id'      => null,
+            'start_dt'         => '2026-05-10 14:00:00',
+            'end_dt'           => '2026-05-10 15:00:00',
+            'duration_minutes' => '60',
+            'is_booked'        => '1',
+            'recurrence_group' => '7',
         ];
 
         $slot = AvailabilitySlot::fromRow($row);
 
         self::assertSame(7, $slot->id);
         self::assertSame(3, $slot->instructorId);
+        self::assertNull($slot->offeringId);
+        self::assertSame(60, $slot->durationMinutes);
+        self::assertSame(7, $slot->recurrenceGroup);
         self::assertTrue($slot->isBooked);
     }
 
     public function testToArrayContainsExpectedKeys(): void
     {
-        $slot = new AvailabilitySlot(1, '2026-04-01 09:00:00', '2026-04-01 10:00:00', false, 10);
+        $slot = new AvailabilitySlot(1, '2026-04-01 09:00:00', '2026-04-01 10:00:00', 30, 8, false, null, 10);
         $arr  = $slot->toArray();
 
-        self::assertArrayHasKey('id', $arr);
-        self::assertArrayHasKey('instructor_id', $arr);
-        self::assertArrayHasKey('start_dt', $arr);
-        self::assertArrayHasKey('end_dt', $arr);
-        self::assertArrayHasKey('is_booked', $arr);
-    }
-
-    public function testDefaultIsBookedIsFalse(): void
-    {
-        $slot = new AvailabilitySlot(1, '2026-04-01 09:00:00', '2026-04-01 10:00:00');
-        self::assertFalse($slot->isBooked);
-    }
-
-    public function testDefaultIdIsNull(): void
-    {
-        $slot = new AvailabilitySlot(1, '2026-04-01 09:00:00', '2026-04-01 10:00:00');
-        self::assertNull($slot->id);
+        foreach (['id', 'instructor_id', 'offering_id', 'start_dt', 'end_dt', 'duration_minutes', 'is_booked', 'recurrence_group'] as $key) {
+            self::assertArrayHasKey($key, $arr);
+        }
     }
 }