Content Scanner Service (#5826)

* implemented the content scanner service with caching and a way to use in the state store context

* fix swiftformat comment enforcing

* pr suggestions

ElementX/Sources/Services/ContentScanner/ContentScannerProxyProtocol.swift

@@ -0,0 +1,21 @@
+//
+// Copyright 2026 Element Creations Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Foundation
+
+enum ContentScannerProxyError: Error {
+    case missingClient
+    case sdkError(Error)
+}
+
+// sourcery: AutoMockable
+/// A thin wrapper around the SDK's content scanner. Given a media source it asks the scanner server
+/// whether the content is clean (safe). It holds no state and no product logic - see
+/// ``ContentScannerServiceProtocol`` for caching, per-event tracking and validation state.
+protocol ContentScannerProxyProtocol: Sendable {
+    func scan(mediaSource: MediaSourceProxy) async -> Result<Bool, ContentScannerProxyError>
+}