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]>

src/BlockPreview.php

@@ -118,11 +118,13 @@ class BlockPreview {
 			: '<p>' . esc_html__( 'A sample class shown so the page can be styled.', 'unsupervised-schedular' ) . '</p>';
 
 		return sprintf(
-			'<div id="us-group-app">%s<div id="us-group-list"><div class="us-class"><h3>%s</h3><p class="us-class-when">%s</p>%s<p>25.00 CAD</p><p class="us-enrol-deadline">%s</p><button type="button" class="us-enrol-btn" disabled>%s</button></div></div></div>',
+			'<div id="us-group-app">%s<div id="us-group-list"><div class="us-class"><h3>%s</h3><p class="us-class-when">%s</p>%s<p class="us-class-price">%s</p><p class="us-enrol-deadline">%s</p><button type="button" class="us-enrol-btn" disabled>%s</button></div></div></div>',
 			self::note( $note ),
 			esc_html__( 'Beginner Group Class', 'unsupervised-schedular' ),
 			esc_html__( 'Saturdays 10:00 AM–11:00 AM', 'unsupervised-schedular' ),
 			$description,
+			// Prices on the live page always carry their cadence, so the sample does too.
+			esc_html__( '25.00 CAD up front', 'unsupervised-schedular' ),
 			esc_html__( 'Enrol by Sep 6, 2026', 'unsupervised-schedular' ),
 			esc_html__( 'Enrol', 'unsupervised-schedular' )
 		);

src/ShortcodeRegistrar.php

@@ -64,14 +64,20 @@ class ShortcodeRegistrar {
 			'nonce'       => wp_create_nonce( 'wp_rest' ),
 			'stripeKey'   => $settings->publishableKey(),
 			'startOfWeek' => Val::int( get_option( 'start_of_week', 1 ) ),
+			// The studio HST rate, so a price quoted to a student on the way in
+			// matches the total they are actually billed.
+			'taxRate'     => $settings->hstRate(),
 		];
 
 		// Attach the shared config to the payment helper so it is defined before the
 		// booking/group scripts (which depend on it) run.
 		wp_localize_script( 'us-scheduler-payment', 'usScheduler', $data );
 
-		wp_register_script( 'us-scheduler', USC_PLUGIN_URL . 'assets/js/booking.js', [ 'us-scheduler-payment' ], USC_VERSION, true );
-		wp_register_script( 'us-scheduler-group', USC_PLUGIN_URL . 'assets/js/group-classes.js', [ 'us-scheduler-payment' ], USC_VERSION, true );
+		// Price formatting and the pay agreement, shared by booking and enrolment.
+		wp_register_script( 'us-scheduler-pricing', USC_PLUGIN_URL . 'assets/js/pricing.js', [ 'us-scheduler-payment' ], USC_VERSION, true );
+
+		wp_register_script( 'us-scheduler', USC_PLUGIN_URL . 'assets/js/booking.js', [ 'us-scheduler-pricing' ], USC_VERSION, true );
+		wp_register_script( 'us-scheduler-group', USC_PLUGIN_URL . 'assets/js/group-classes.js', [ 'us-scheduler-pricing' ], USC_VERSION, true );
 
 		// Progressive enhancement for the two-step registration form (no dependencies).
 		wp_register_script( 'us-scheduler-register', USC_PLUGIN_URL . 'assets/js/register.js', [], USC_VERSION, true );