Store the user profile off the main thread when it is updated by the SDK

Same issue as when refreshing the profile manually: the profile listener stored the profile (Base64 encoding and session database access) from the session coroutine scope, which runs on the main thread.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClient.kt

@@ -322,7 +322,7 @@ class RustMatrixClient(
         override fun onUpdate(profile: UserProfile) {
             val matrixUser = profile.map()
             _userProfile.tryEmit(matrixUser)
-            sessionCoroutineScope.launch {
+            sessionCoroutineScope.launch(sessionDispatcher) {
                 storeUserProfile(matrixUser)
             }
         }