View a policy version's content, and make policy text readable

The Policies admin page listed versions but never showed what any of them
said, so revising a policy meant retyping it blind into an empty draft box.
Each version row now has a View action that renders that version's text on
the page, editable in place. A draft is saved back to itself; editing a
published or archived version branches a new draft and leaves the original
alone, because acceptances are recorded against policy_version_id and text a
student agreed to must stay exactly as they saw it.

That viewer also exposed why a studio reported the acceptance box as
unreadable — one squashed line, overlapping words, a horizontal scrollbar.
Bodies are typed into a bare textarea, so most carry no markup, and the raw
text was emitted with its blank lines intact but nothing to turn them into
paragraphs. PolicyVersion::bodyHtml() now renders every body the way
WordPress renders post content (kses, then wpautop) and feeds all three
consumers: the booking/enrolment JSON, the signup form, and the new viewer.
Bodies written with markup are unaffected.

The other half was that .us-policy-body had no CSS whatsoever and inherited
whatever the theme did with an unstyled block in a form. It is now a bounded
reading box that scrolls vertically and breaks long tokens, so a pasted URL
cannot force the page sideways and a long policy cannot push the accept
checkbox out of view. RegistrationPage was also never enqueueing the plugin
stylesheet, which is why the signup gate looked worst of all.

Closes #126
Closes #127

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

src/Auth/RegistrationPage.php

@@ -116,6 +116,10 @@ class RegistrationPage {
 		$canRegister       = $open || $inviteValid;
 		$inviteOnlyMessage = $this->inviteOnlyMessage( $atts );
 
+		// The signup form carries the same policy-acceptance markup as the booking
+		// gate, so it needs the plugin stylesheet that formats it.
+		wp_enqueue_style( 'us-scheduler' );
+
 		// The two-step script only matters when there is a second step to reveal.
 		if ( $canRegister && '' === $successType && [] !== $accountQuestions ) {
 			wp_enqueue_script( 'us-scheduler-register' );