US-17 — Record notification audit information

## User story

As a notification administrator, I want to see who last changed a notification and when so that changes can be traced.

## Acceptance scenarios

```gherkin
Feature: Record notification audit information

Scenario: Record notification creation
When an author creates a notification
Then the author should be recorded as the last author
And the creation time should be recorded as the last modified time

Scenario: Record a notification update
Given a notification already exists
When an author saves a change
Then the current author should be recorded as the last author
And the last modified date and time should be updated

Scenario: Display audit information
When the notification list is displayed
Then each notification should show its last modified date and time
And each notification should show its last author
```

No files or tests are named. Start by locating the notification creation and update entry points, then trace how the notification list is assembled and displayed. Done means creation and later saves record the current author and modification time, and the list shows both values for every notification.

Written by the indexing model from the issue text.