panel: polish rate-limit form copy and field alignment

Drop the app L1 backstop line, move trusted-IP help under the IP field,
shorten the domain rate-limit title, and align field-pair labels with DMARC.

Co-authored-by: Cursor <cursoragent@cursor.com>

CHANGELOG.md

@@ -7,12 +7,12 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); version
 
 ### Changed
 
-- panel: level-1 backstop is shown as muted copy (`N messages / Ws — Settings`)
-  and in message-limit labels; Settings uses a code-row for the L1 value. Domain
-  and application rate-limit status uses the shared `st` badge (`active` /
-  `inactive — level 1 only`). Trusted-IP override copy is a single paragraph;
-  domain rate-limit help sits above Save; Address mode drops the duplicate
-  field label.
+- panel: level-1 backstop is shown as muted copy on the domain form
+  (`N messages / Ws — Settings`) and in message-limit labels; Settings uses a
+  code-row for the L1 value. Domain and application rate-limit status uses the
+  shared `st` badge. Trusted-IP help sits under the IP field; domain rate-limit
+  help sits above Save; Address mode drops the duplicate field label; field-pair
+  top spacing aligns with paired DMARC labels.
 
 ## [1.2.4] - 2026-08-12