fix(e2e): read setup-token via exec; reclaim /data

Container startup is green; CI failed because panel-owned setup-token (0600)
was unreadable on the host bind mount, and TempDir cleanup hit EACCES on
sqlite/opendkim files. Read the token with compose exec (as guide.md) and
chown /data before removing containers/stage.

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

build/postfix-config.sh

@@ -245,7 +245,7 @@ EOF
 # Validate the generated configuration; fail loudly if postconf produced
 # anything Postfix rejects, before the wrapper tries to start it.
 # #region agent log
-pcstep "pre-check maillog=$(postconf -qh maillog_file 2>&1) prefixes=$(postconf -qh maillog_file_prefixes 2>&1) postlog=$(postconf -qM postlog/unix-dgram 2>&1)"
+pcstep "pre-check maillog=$(postconf -h maillog_file 2>&1) prefixes=$(postconf -h maillog_file_prefixes 2>&1) postlog=$(postconf -M postlog/unix-dgram 2>&1)"
 # #endregion
 pcstep "postfix check"
 set +e
@@ -260,8 +260,8 @@ if [ "$ec" -ne 0 ]; then
 	cat "$MAIL_LOG_PATH" 2>&1 >&2 || true
 	# #region agent log
 	echo "postfix-config: --- postconf dump (debug) ---" >&2
-	postconf -qh maillog_file maillog_file_prefixes 2>&1 >&2 || true
-	postconf -qM postlog/unix-dgram 2>&1 >&2 || true
+	postconf -h maillog_file maillog_file_prefixes 2>&1 >&2 || true
+	postconf -M postlog/unix-dgram 2>&1 >&2 || true
 	# #endregion
 	exit "$ec"
 fi