feat(share): add ShareReviewAccessCheckEvent to OCP public API

Introduces OCP\Share\Events\ShareReviewAccessCheckEvent as the canonical
authorization gate event for ShareReview sources. The event carries the
source name and share ID for listener context, implements deny-wins
semantics, and stops propagation immediately on denial.

Assisted-by: ClaudeCode:claude-sonnet-4-6
Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

Author: AndyScherzinger

lib/public/Share/Events/ShareReviewAccessCheckEvent.php

@@ -0,0 +1,130 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\Share\Events;
+
+use OCP\AppFramework\Attribute\Consumable;
+use OCP\EventDispatcher\Event;
+
+/**
+ * Authorization gate event dispatched by a ShareReview source before deleting
+ * an app-managed share on behalf of a ShareReview operator.
+ *
+ * Usage — dispatch and check:
+ *
+ *   $event = new ShareReviewAccessCheckEvent('MyApp', $shareId);
+ *   $dispatcher->dispatchTyped($event);
+ *   if (!$event->isHandled() || !$event->isGranted()) {
+ *       return false; // default-deny: no listener means no access
+ *   }
+ *
+ * Semantics:
+ *  - Default-deny: an unhandled event blocks the deletion.
+ *  - Deny wins: once denyAccess() is called, further grantAccess() calls are
+ *    ignored and propagation is stopped immediately.
+ *  - Multiple grants are harmless; the last listener to deny is authoritative.
+ *
+ * @since 34.0.2
+ */
+#[Consumable(since: '34.0.2')]
+class ShareReviewAccessCheckEvent extends Event {
+
+	private bool $handled = false;
+	private bool $granted = false;
+	private ?string $reason = null;
+
+	/**
+	 * @param string $sourceName Stable, non-translated identifier for the app
+	 *                           registering the share source (e.g. 'Deck', 'Tables').
+	 * @param string $shareId App-internal identifier of the share being deleted.
+	 *
+	 * @since 34.0.2
+	 */
+	public function __construct(
+		private readonly string $sourceName,
+		private readonly string $shareId,
+	) {
+		parent::__construct();
+	}
+
+	/**
+	 * Stable, non-translated identifier of the app that owns this share source.
+	 *
+	 * @since 34.0.2
+	 */
+	public function getSourceName(): string {
+		return $this->sourceName;
+	}
+
+	/**
+	 * App-internal identifier of the share being deleted.
+	 *
+	 * @since 34.0.2
+	 */
+	public function getShareId(): string {
+		return $this->shareId;
+	}
+
+	/**
+	 * Grant access to delete the share.
+	 *
+	 * Has no effect if denyAccess() was already called on this event — deny wins.
+	 *
+	 * @since 34.0.2
+	 */
+	public function grantAccess(): void {
+		if ($this->handled && !$this->granted) {
+			return; // deny wins — a prior denyAccess() cannot be escalated to a grant
+		}
+		$this->handled = true;
+		$this->granted = true;
+	}
+
+	/**
+	 * Deny access and provide a human-readable reason.
+	 *
+	 * Stops event propagation immediately — no further listeners will run.
+	 *
+	 * @since 34.0.2
+	 */
+	public function denyAccess(string $reason): void {
+		$this->handled = true;
+		$this->granted = false;
+		$this->reason = $reason;
+		$this->stopPropagation();
+	}
+
+	/**
+	 * Whether any listener has responded to this event.
+	 *
+	 * @since 34.0.2
+	 */
+	public function isHandled(): bool {
+		return $this->handled;
+	}
+
+	/**
+	 * Whether access was granted.
+	 *
+	 * @since 34.0.2
+	 */
+	public function isGranted(): bool {
+		return $this->granted;
+	}
+
+	/**
+	 * Human-readable denial reason, or null if access was granted or the event
+	 * has not been handled yet.
+	 *
+	 * @since 34.0.2
+	 */
+	public function getReason(): ?string {
+		return $this->reason;
+	}
+}