panel: show the subject as text, not as its MIME encoding

A non-Latin subject arrives as RFC 2047 encoded-words, which the send-log
printed verbatim: unreadable, and one unbreakable run wide enough to push the
Status column out of its card. Decode at journal time (UTF-8/ASCII; exotic
charsets keep the raw header) and cap at 200 characters, then clip the column
to one line with the full text in the tooltip so no subject can widen the row.

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

CHANGELOG.md

@@ -5,6 +5,18 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); version
 
 ## [Unreleased]
 
+### Fixed
+
+- panel: Deliveries now shows the subject as text rather than as its MIME
+  encoding. A subject in any non-Latin alphabet reaches the milter as RFC 2047
+  encoded-words (`=?utf-8?Q?=D0=9F…?=`), and the panel printed that verbatim —
+  unreadable, and as one unbreakable run wide enough to push the Status column
+  outside the card. Subjects are decoded when the message is journalled and
+  capped at 200 characters; the column clips anything still too long to one
+  line, with the full text in the tooltip. Rows logged before this release keep
+  their raw string. Subjects in the legacy single-byte charsets (windows-1251,
+  koi8-r) are still stored as sent — there is no decoder for them.
+
 ## [0.3.0] - 2026-08-03
 
 ### Fixed