Show price cadence and require a pay agreement at booking

Every price a student meets on the front end now carries the cadence it is
billed on — at booking, up front, weekly, monthly — so a bare amount can no
longer read as a one-off when it is a recurring charge.

Both registration forms then restate the price and require a second, separate
tick agreeing to pay it, distinct from the policy acceptances above it. The
agreed figure includes the studio HST so it matches Payment::total(), the amount
actually billed; the rate reaches the browser as a new localized `taxRate`.

A weekly reservation is charged per lesson for every week it claims, and a week
another student takes first is simply not claimed, so its total is quoted as a
ceiling ("up to 12 lessons") rather than a promise. Free offerings have nothing
to agree to and show no price block at all.

The formatting and the agreement live in one shared helper (`window.usPricing`,
registered as `us-scheduler-pricing`) so a price reads the same in the booking
form, the class catalogue and the editor preview.

Closes #124

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

tests/Unit/ShortcodeRegistrarTest.php

@@ -23,6 +23,9 @@ class ShortcodeRegistrarTest extends TestCase
     /** @var array<string, callable> */
     private array $shortcodes = [];
 
+    /** @var array<string, mixed> */
+    private array $localized = [];
+
     protected function setUp(): void
     {
         parent::setUp();
@@ -84,6 +87,69 @@ class ShortcodeRegistrarTest extends TestCase
         self::assertSame('group', $this->shortcodes['us_group_classes'](''));
     }
 
+    /**
+     * The booking and group-class scripts both read prices through the shared
+     * pricing helper, so it must be registered ahead of them (and behind the
+     * payment helper, which carries the localized config it reads).
+     */
+    public function testPricingHelperIsRegisteredAheadOfTheBookingAndGroupScripts(): void
+    {
+        $scripts = $this->captureEnqueuedAssets();
+
+        self::assertSame(['us-scheduler-payment'], $scripts['us-scheduler-pricing']);
+        self::assertSame(['us-scheduler-pricing'], $scripts['us-scheduler']);
+        self::assertSame(['us-scheduler-pricing'], $scripts['us-scheduler-group']);
+    }
+
+    /**
+     * The studio HST rate reaches the front end so a price quoted on a booking
+     * form matches the total the student is actually billed.
+     */
+    public function testStudioTaxRateIsLocalizedToTheFrontEnd(): void
+    {
+        $this->captureEnqueuedAssets();
+
+        self::assertSame(13.0, $this->localized['taxRate']);
+    }
+
+    /**
+     * @return array<string, array<int, string>> Registered script handle => dependencies.
+     */
+    private function captureEnqueuedAssets(): array
+    {
+        $scripts   = [];
+        $localized = &$this->localized;
+
+        Functions\when('wp_register_style')->justReturn(true);
+        Functions\when('rest_url')->justReturn('https://example.test/wp-json/us-scheduler/v1/');
+        Functions\when('wp_create_nonce')->justReturn('nonce');
+        Functions\when('get_option')->alias(
+            static fn (string $name, mixed $default = false): mixed => match ($name) {
+                'us_hst_rate' => '13',
+                'start_of_week' => 1,
+                default => $default,
+            }
+        );
+        Functions\when('wp_register_script')->alias(
+            static function (string $handle, string $src, array $deps = []) use (&$scripts): bool {
+                $scripts[$handle] = $deps;
+
+                return true;
+            }
+        );
+        Functions\when('wp_localize_script')->alias(
+            static function (string $handle, string $object, array $data) use (&$localized): bool {
+                $localized = $data;
+
+                return true;
+            }
+        );
+
+        $this->registrar->enqueueAssets();
+
+        return $scripts;
+    }
+
     public function testShortcodeAttributesArePassedThroughUnchanged(): void
     {
         $this->registrar->register();