Add the bones of an Email Notification service

src/notifications/data.py

@@ -0,0 +1,38 @@
+from dataclasses import dataclass, field
+
+URL = str
+
+
+@dataclass
+class NotificationAction:
+    # A unique identifier for the action
+    action: str
+    # The title to show with the action
+    title: str
+    # Where to navigate to when clicked.
+    navigate: URL | None = None
+
+
+@dataclass
+class Notification:
+    """
+    Details to show in a notification
+
+    Much of the data here is intended to match the arguments to the [showNotification](https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerRegistration/showNotification)
+    Web API, but this content is ideally displayable in other contexts (for example in Email or RSS)
+    """
+
+    # The main title content to show
+    title: str
+    # The content of the notification
+    content: str
+
+    # The UNIX timestamp in milliseconds since the epoch associated with this notification
+    timestamp: int
+    # A list of actions included with this notification
+    actions: list[NotificationAction] = field(default_factory=list)
+    # The location of an icon to show as the icon for this notification
+    icon: URL | None = None
+
+    # The location of an image associated with this notification
+    image: URL | None = None