Fix local room encryption status always not enabled (#30461)

* Fix local room encryption status always not enabled

* refactor: put back the e2e test after merge

* fix: look at e2eStatus in composer of local room

* doc: add docs to `LocalRoom.isEncryptionEnabled`

* test(e2e): check composer doesn't display unencrypted state

* test: update existing tests

* test(e2e): update existing tests

* refactor: move room encryption check in a dedicated function

* refactor: make `isEncryptionEnabled` cleaner

* test: add tests for `LocalRoom.isEncrypted`

* doc: fix `useIsEncrypted` comment

---------

Co-authored-by: Florian Duros <florian.duros@ormaz.fr>

src/models/LocalRoom.ts

@@ -6,7 +6,14 @@ SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Com
 Please see LICENSE files in the repository root for full details.
 */
 
-import { type MatrixClient, Room, PendingEventOrdering } from "matrix-js-sdk/src/matrix";
+import {
+    type MatrixClient,
+    Room,
+    PendingEventOrdering,
+    MatrixEvent,
+    Direction,
+    EventType,
+} from "matrix-js-sdk/src/matrix";
 
 import { type Member } from "../utils/direct-messages";
 
@@ -50,4 +57,20 @@ export class LocalRoom extends Room {
     public get isError(): boolean {
         return this.state === LocalRoomState.ERROR;
     }
+
+    /**
+     * Check if encryption is enabled in this room.
+     * True if the room has any encryption state event
+     */
+    public isEncryptionEnabled(): boolean {
+        const roomState = this.getLiveTimeline().getState(Direction.Forward);
+        if (!roomState) return false;
+
+        const stateEvents = roomState.getStateEvents(EventType.RoomEncryption);
+        if (stateEvents.length === 0) return false;
+
+        // if there is an encryption state event, it is encrypted.
+        // Regardless of the content/algorithm, we assume it is encrypted.
+        return stateEvents[0] instanceof MatrixEvent;
+    }
 }