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>

tests/Unit/Policy/PolicyServiceTest.php

@@ -0,0 +1,91 @@
+<?php
+declare(strict_types=1);
+
+namespace Unsupervised\Schedular\Tests\Unit\Policy;
+
+use Brain\Monkey\Functions;
+use Mockery;
+use Unsupervised\Schedular\Policy\Policy;
+use Unsupervised\Schedular\Policy\PolicyRepository;
+use Unsupervised\Schedular\Policy\PolicyService;
+use Unsupervised\Schedular\Policy\PolicyVersion;
+use Unsupervised\Schedular\Policy\PolicyVersionRepository;
+use Unsupervised\Schedular\Tests\Unit\TestCase;
+
+class PolicyServiceTest extends TestCase
+{
+    private PolicyRepository $policies;
+    private PolicyVersionRepository $versions;
+    private PolicyService $service;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->policies = Mockery::mock(PolicyRepository::class);
+        $this->versions = Mockery::mock(PolicyVersionRepository::class);
+        $this->service  = new PolicyService($this->policies, $this->versions);
+    }
+
+    public function testCreatePolicyInsertsPolicy(): void
+    {
+        $this->policies->shouldReceive('insert')
+            ->once()
+            ->with(Mockery::on(static fn (Policy $p): bool => $p->title === 'Cancellation' && $p->slug === 'cancellation'))
+            ->andReturn(7);
+
+        self::assertSame(7, $this->service->createPolicy('Cancellation', 'cancellation'));
+    }
+
+    public function testAddDraftVersionNumbersAfterLatest(): void
+    {
+        $this->versions->shouldReceive('maxVersionNumber')->once()->with(4)->andReturn(2);
+        $this->versions->shouldReceive('insert')
+            ->once()
+            ->with(Mockery::on(static function (PolicyVersion $v): bool {
+                return $v->policyId === 4
+                    && $v->versionNumber === 3
+                    && $v->status === PolicyVersion::STATUS_DRAFT;
+            }))
+            ->andReturn(15);
+
+        self::assertSame(15, $this->service->addDraftVersion(4, '<p>draft</p>'));
+    }
+
+    public function testPublishArchivesPriorCurrentAndPointsPolicyAtNewVersion(): void
+    {
+        Functions\expect('current_time')->with('mysql')->andReturn('2026-06-01 12:00:00');
+
+        $this->policies->shouldReceive('findById')->once()->with(4)->andReturn(new Policy('T', 't', 8, 4));
+        $this->versions->shouldReceive('findById')->once()->with(9)->andReturn(new PolicyVersion(4, 2, '<p>x</p>', PolicyVersion::STATUS_DRAFT, null, 9));
+
+        $this->versions->shouldReceive('updateStatus')->once()->with(8, PolicyVersion::STATUS_ARCHIVED);
+        $this->versions->shouldReceive('updateStatus')->once()->with(9, PolicyVersion::STATUS_PUBLISHED, '2026-06-01 12:00:00');
+        $this->policies->shouldReceive('updateCurrentVersion')->once()->with(4, 9)->andReturn(true);
+
+        self::assertTrue($this->service->publishVersion(4, 9));
+    }
+
+    public function testPublishFirstVersionDoesNotArchive(): void
+    {
+        Functions\expect('current_time')->andReturn('2026-06-01 12:00:00');
+
+        $this->policies->shouldReceive('findById')->once()->with(4)->andReturn(new Policy('T', 't', null, 4));
+        $this->versions->shouldReceive('findById')->once()->with(9)->andReturn(new PolicyVersion(4, 1, null, PolicyVersion::STATUS_DRAFT, null, 9));
+
+        // No archive call expected (no prior current version).
+        $this->versions->shouldReceive('updateStatus')->once()->with(9, PolicyVersion::STATUS_PUBLISHED, '2026-06-01 12:00:00');
+        $this->policies->shouldReceive('updateCurrentVersion')->once()->with(4, 9)->andReturn(true);
+
+        self::assertTrue($this->service->publishVersion(4, 9));
+    }
+
+    public function testPublishRejectsVersionFromAnotherPolicy(): void
+    {
+        $this->policies->shouldReceive('findById')->once()->with(4)->andReturn(new Policy('T', 't', null, 4));
+        $this->versions->shouldReceive('findById')->once()->with(9)->andReturn(new PolicyVersion(99, 1, null, PolicyVersion::STATUS_DRAFT, null, 9));
+
+        // No status/current-version writes when the version belongs elsewhere.
+        self::assertFalse($this->service->publishVersion(4, 9));
+    }
+}