Add session expiry renewal flow

scripts/autoload/exam_simulation_service.gd

@@ -21,6 +21,7 @@ var history_next_cursor := ""
 var is_loading := false
 var pending_action := ""
 var request_queue: Array = []
+var request_access_token := ""
 
 
 func _ready() -> void:
@@ -122,14 +123,15 @@ func _send(action: String, method: int, suffix: String, payload: Dictionary = {}
 
 
 func _send_absolute(action: String, method: int, url: String, payload: Dictionary = {}) -> void:
-	if AuthState.access_token == "":
+	if not AuthState.can_send_authenticated_request():
 		return
 	if is_loading:
 		request_queue.append({"action": action, "method": method, "url": url, "payload": payload.duplicate(true)})
 		return
 	is_loading = true
 	pending_action = action
-	var headers := PackedStringArray(["Authorization: Bearer %s" % AuthState.access_token])
+	request_access_token = AuthState.access_token
+	var headers := PackedStringArray(["Authorization: Bearer %s" % request_access_token])
 	var body := ""
 	if not payload.is_empty():
 		headers.append("Content-Type: application/json")
@@ -146,6 +148,8 @@ func _on_request_completed(result: int, response_code: int, _headers: PackedStri
 	pending_action = ""
 	is_loading = false
 	call_deferred("_process_request_queue")
+	if response_code == 401:
+		AuthState.handle_unauthorized(request_access_token)
 	if result != HTTPRequest.RESULT_SUCCESS or response_code < 200 or response_code >= 300:
 		var server_message := body.get_string_from_utf8().strip_edges()
 		if server_message.length() > 240: