Add Policies domain (drafting, versioning, tracked acceptance)

Implements #6: studio admins draft, version, and publish policies; the
public registration gate reads the current published version of each, and
acceptance is recorded against the exact version so a new version must be
re-accepted at the next booking.

- src/Policy/: Policy, PolicyVersion, PolicyAcceptance value objects;
  PolicyRepository, PolicyVersionRepository, AcceptanceRepository;
  PolicyService (orchestrates create/add-draft/publish across the policies
  and versions tables); PolicyEndpoint (REST); PolicyController +
  templates/admin/policies.php (Policies admin menu, manage_policies)
- us_policies, us_policy_versions, us_policy_acceptances tables in Schema
- REST: public GET /policies (current published versions); manage_policies
  for create, add version, edit draft, and publish
- Wiring in Plugin, RestRegistrar, AdminMenu

AcceptanceRepository is built now and consumed by the booking/enrolment
gate in #3/#4.

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

Tests: tests/Unit/Policy/ (value objects, repositories, service).
composer test (90 total), cs, and PHPStan level 6 all pass.

Refs #6

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/RestRegistrar.php

@@ -9,6 +9,10 @@ use Unsupervised\Schedular\Booking\BookingEndpoint;
 use Unsupervised\Schedular\Booking\BookingRepository;
 use Unsupervised\Schedular\Offering\OfferingEndpoint;
 use Unsupervised\Schedular\Offering\OfferingRepository;
+use Unsupervised\Schedular\Policy\PolicyEndpoint;
+use Unsupervised\Schedular\Policy\PolicyRepository;
+use Unsupervised\Schedular\Policy\PolicyService;
+use Unsupervised\Schedular\Policy\PolicyVersionRepository;
 use Unsupervised\Schedular\Registration\QuestionEndpoint;
 use Unsupervised\Schedular\Registration\QuestionRepository;
 
@@ -20,12 +24,14 @@ class RestRegistrar {
 	private BookingEndpoint $bookingEndpoint;
 	private OfferingEndpoint $offeringEndpoint;
 	private QuestionEndpoint $questionEndpoint;
+	private PolicyEndpoint $policyEndpoint;
 
-	public function __construct( AvailabilityRepository $availability, BookingRepository $bookings, OfferingRepository $offerings, QuestionRepository $questions ) {
+	public function __construct( AvailabilityRepository $availability, BookingRepository $bookings, OfferingRepository $offerings, QuestionRepository $questions, PolicyRepository $policies, PolicyVersionRepository $policyVersions, PolicyService $policyService ) {
 		$this->availabilityEndpoint = new AvailabilityEndpoint( $availability );
 		$this->bookingEndpoint      = new BookingEndpoint( $availability, $bookings );
 		$this->offeringEndpoint     = new OfferingEndpoint( $offerings );
 		$this->questionEndpoint     = new QuestionEndpoint( $questions, $offerings );
+		$this->policyEndpoint       = new PolicyEndpoint( $policies, $policyVersions, $policyService );
 	}
 
 	public function register(): void {
@@ -37,5 +43,6 @@ class RestRegistrar {
 		$this->bookingEndpoint->registerRoutes( self::NAMESPACE );
 		$this->offeringEndpoint->registerRoutes( self::NAMESPACE );
 		$this->questionEndpoint->registerRoutes( self::NAMESPACE );
+		$this->policyEndpoint->registerRoutes( self::NAMESPACE );
 	}
 }