Display a badge for messages decrypted using shared keys. (#4937)

* feat: Show info badge for messages decrypted with shared keys

* tests: Add snapshots and tests for forwarder icon.

* fix: Update `EventBasedTimelineItemProtocol.hasStatusIcon`

* fix: Address review comments.

* fix: Use two translations for key forwarded dialog content.

* refactor: Rename `TimelineItemForwarder` to `TimelineItemKeyForwarder`.

Additionally adds a `[weak self]` guard to `encryptionForwarder` alert
handler.

* tests: Add `previewLayout` directive to `encryptionForwarder` previews

* refactor: Remove unused translations, use short-circuiting condition.

ElementX/Sources/Services/Timeline/TimelineItemContent/TimelineItemKeyForwarder.swift

@@ -0,0 +1,38 @@
+//
+// 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 MatrixRustSDK
+import SwiftUI
+
+struct TimelineItemKeyForwarder: Identifiable, Hashable {
+    let id: String
+    let displayName: String?
+    
+    init(id: String, displayName: String? = nil) {
+        self.id = id
+        self.displayName = displayName
+    }
+    
+    init(forwarderID: String, forwarderProfile: ProfileDetails) {
+        switch forwarderProfile {
+        case let .ready(displayName, _, _):
+            self.init(id: forwarderID,
+                      displayName: displayName)
+        default:
+            self.init(id: forwarderID,
+                      displayName: nil)
+        }
+    }
+    
+    var message: String {
+        if let displayName {
+            L10n.cryptoEventKeyForwardedKnownProfileDialogContent(displayName, id)
+        } else {
+            L10n.cryptoEventKeyForwardedUnknownProfileDialogContent(id)
+        }
+    }
+}