test(e2e): follow the panel's markup for applications and the send log

Two scrapes had drifted from the pages they read, and the suite has not
been run since either page changed.

applicationID still looked for an application as a table row
(<td class="code">login</td> ... /applications/N/mode). Applications became
a list of blocks in d35b309, so the lookup had been failing for several
commits, including the one currently deployed — this is stale test, not a
regression. It now anchors on the login heading and takes the id from the
first action posted under it, whichever that is, so reordering a block's
controls will not break it again.

The level-2 rate-limit check looked for the application's login among the
send-log rows. 997af18 took that column off the log — the log identifies a
message and names the application only on a row's own page — so the check
now filters the log by application instead. That is the same attribution
through a server-side WHERE app_login rather than a substring match on
rendered HTML.

Verified on selfpost.example.com: make e2e green, all subtests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

test/e2e/main_test.go

@@ -166,7 +166,7 @@ func TestE2E(t *testing.T) {
 		}
 
 		if err := waitFor("send-log row to reach status=sent", 30*time.Second, 500*time.Millisecond, func() (bool, error) {
-			rows, err := sc.panel.sendLogRows(senderDomain)
+			rows, err := sc.panel.sendLogRows(senderDomain, "")
 			if err != nil {
 				return false, err
 			}