Event log: only the newest event expanded, and only the 50 most recent (closes #349)

The event log now loads only the 50 newest events, limited in its query, and only the newest starts expanded; the rest start collapsed. Paging is removed rather than capped, since 50 events never need a second page: the Previous and Next links, the `page` query parameter and the page number Replay and Resubmit carried back are gone, and a `?page=` left in an old link shows the 50 newest. A webhook with more than 50 events reads "50 most recent of N events" beside the heading. Comments and a README line that called `page` the only query parameter the service reads now name `next` and `notice`.

Model: opus-5-5

internal/handlers/event_log_view_test.go

@@ -75,9 +75,7 @@ func seedAndProject(
 	wh := seedWebhook(t, db)
 	seedEventWithBody(t, dbMgr, wh.ID, body)
 
-	views := h.LoadEventLogViewsForTest(
-		httptest.NewRecorder(), *wh, 1,
-	)
+	views := h.LoadEventLogViewsForTest(httptest.NewRecorder(), *wh)
 	require.Len(t, views, 1)
 
 	return views[0]