fix: pin logrotate config mode in image and fail loud on bad permissions

COPY --chmod makes /etc/logrotate.d/mail 0644 regardless of build context
file modes (Windows tar sync). logrotate-loop preflight exits non-zero when
logrotate would ignore the config. E2e covers mode, forced rotation, and a
group-writable context build.

Co-Authored-By: Composer 2.5 <noreply@cursor.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

build/supervisord.conf

@@ -104,8 +104,9 @@ stderr_logfile=/dev/stderr
 stderr_logfile_maxbytes=0
 
 ; Periodic logrotate for /data/log/mail.log (spec 9, 10: daily, 7-14 files kept
-; in the image). Runs as root so logrotate can read/rotate the log; never exits
-; non-zero, so it neither trips the crashexit listener nor needs restarting.
+; in the image). Runs as root so logrotate can read/rotate the log. Exits
+; non-zero when the config is group/other-writable (logrotate would ignore it
+; silently); autorestart surfaces BACKOFF on the Status page.
 [program:logrotate]
 command=/usr/local/bin/logrotate-loop.sh
 priority=400