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/export_test.go

@@ -51,12 +51,6 @@ const (
 	SidecarLeftMsgForTest = sidecarLeftMsg
 )
 
-// PageOrFirstForTest exposes pageOrFirst for use in the handlers_test
-// package.
-func PageOrFirstForTest(s string) int {
-	return pageOrFirst(s)
-}
-
 // DummyVerificationsForTest reports how many equivalent-cost
 // verifications were charged for usernames that do not exist. It
 // lets a test prove the anti-enumeration path ran without timing
@@ -79,10 +73,9 @@ func TrimPartialRuneForTest(b []byte) []byte {
 func (s *Handlers) LoadEventLogViewsForTest(
 	w http.ResponseWriter,
 	webhook database.Webhook,
-	page int,
 ) []EventLogView {
 	views, _, _ := s.loadEventsWithDeliveries(
-		w, newRequestForTest(), webhook, nil, page,
+		w, newRequestForTest(), webhook, nil,
 	)
 
 	return views