This commit introduces a new `/api/v1/notifications/live` endpoint that
utilizes Server-Sent Events (SSE) to stream notifications to the web UI.
This is used to display alerts such as when a configuration reload
has failed.
I opted for SSE over WebSockets because SSE is simpler to implement and
more robust for our use case. Since we only need one-way communication
from the server to the client, SSE fits perfectly without the overhead
of establishing and maintaining a two-way WebSocket connection.
When the SSE connection fails, we go back to a classic
/api/v1/notifications API endpoint.
This commit also contains the required UI changes for the new Mantine UI.
Signed-off-by: Julien <roidelapluie@o11y.eu>
