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

The event log now loads the 50 newest events in its query and opens
only the newest on load, as the recent events on a webhook's page
already do. With 50 at most there is never a second page, so paging is
gone: the page links, the `page` query parameter, the page number that
Replay and Resubmit carried back to the log, and `pageOrFirst` with its
test. The count beside the heading reads "50 most recent of N events"
when there are more. The comments and README lines that named `page` as
the query parameter the service reads now name `next` and `notice`.

Model: opus-5-5

README.md

@@ -1364,17 +1364,18 @@ an entrypoint's Edit button shows its edit form in place of its description and
 hides until the form closes, Cancel hides the form and drops what was typed, as
 does leaving the page and going back to it, and Save changes the description;
 of the recent events on the webhook page only the newest starts expanded, each
-expands and collapses, and Open leads to the event's own page; an event in the
-event log expands and collapses when its row's caret or its ID is clicked, and
-from the keyboard, but not when its ID is selected with the mouse, and a
-delivery's attempts inside it expand and collapse; and at phone width the menu
-button opens and closes the mobile menu. It also fails if the browser reports a
-console warning or error, an uncaught exception, or anything the policy refused.
-`make check` and the image build lint it but do not run it, and `make test`
-leaves it out (its file is built only with the `browser` build tag). Run it with
-`make test-browser` after changing `templates/` or `static/js/`: that builds
-`Dockerfile.browser`, which runs the test in a digest-pinned headless browser
-image, so the host needs no browser.
+expands and collapses, and Open leads to the event's own page; of the events in
+the event log only the newest starts expanded, and an event there expands and
+collapses when its row's caret or its ID is clicked, and from the keyboard, but
+not when its ID is selected with the mouse, and a delivery's attempts inside it
+expand and collapse; and at phone width the menu button opens and closes the
+mobile menu. It also fails if the browser reports a console warning or error, an
+uncaught exception, or anything the policy refused. `make check` and the image
+build lint it but do not run it, and `make test` leaves it out (its file is
+built only with the `browser` build tag). Run it with `make test-browser` after
+changing `templates/` or `static/js/`: that builds `Dockerfile.browser`, which
+runs the test in a digest-pinned headless browser image, so the host needs no
+browser.
 
 The package's tarball is committed as `3p/alpinejs-csp-3.14.9.tgz`, byte for
 byte as the npm registry publishes it. It is a dependency, not this repo's build
@@ -2536,8 +2537,9 @@ The query string is never logged; it is replaced by the fixed marker
 `/.well-known/healthcheck` and `/s/*` answer 200 to anyone with no rate
 limiter in front of them, so a query on a fixed 200 URL would otherwise
 buy the same amplification as an invented path. Nothing debuggable is
-lost: `page`, on the authenticated pagination links, is the only query
-parameter this service reads.
+lost: the only query parameters this service reads are the login page's
+`next`, the page to return to, and `notice`, which names the line a page
+shows after an action.
 
 Client-supplied request content does not leave the host by the other
 route either. The Sentry SDK attaches the request to every event it