fix(logtail): keep mail.log in /data and reconcile stuck rows (v1.x closure phase 2)

Move the delivery log from the ephemeral /var/log to /data/log/mail.log so
the lines that resolve a queued send-log row survive a container recreate.
postlogd writes it as postfix, the panel reads it through the selfpost group
(dir 2750, file 0640, normalised every start); backups exclude log/.

Close the residual gap with a queue sweep: rows queued for over two minutes
whose id postqueue -p no longer lists are marked bounced. The sweep waits
until the tailer has read the log to its end and does nothing when the queue
cannot be listed, so a message in flight is never touched.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

build/supervisord.conf

@@ -103,7 +103,7 @@ stdout_logfile_maxbytes=0
 stderr_logfile=/dev/stderr
 stderr_logfile_maxbytes=0
 
-; Periodic logrotate for /var/log/mail.log (spec 9, 10: daily, 7-14 files kept
+; 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.
 [program:logrotate]