feat(qsl): OpsLog QSL received marker + PSE/TNX card stamp + default QSL message

Received flag: new APP_OPSLOG_QSL_RCVD extra, toggled on the QSO edit window
next to QSL Message (immediate targeted write via SetOpsLogQSLReceived so it sets
AND clears reliably), plus a live PSE QSL / TNX indicator and a Recent-QSOs
column mirroring the sent one.

PSE/TNX card stamp: automatic — received → TNX, otherwise PSE QSL — exposed as
the {qso.pse_tnx} token (added to qslVars, so preview and send agree) and placed
in the default QSO-box footer; it can be moved to its own element in the designer.

Default QSL message: new qsl.default_message (QSLEmailTemplates.DefaultMessage),
edited under Settings → E-mail → QSL card e-mail. qslVars falls back to it when
the QSO's own QSLMSG is empty, so a per-QSO message always wins. Single choke
point covers both live preview and send.

internal/qslcard/placement.go

@@ -734,7 +734,10 @@ func placeQSOBox(profile ProfileInfo, zone pxRect, occupied []pxRect) QSOBox {
 		BG: "#ffffff", BGOpacity: 0.88, Radius: 12,
 		Title:  "Confirming QSO with {qso.callsign}",
 		Fields: []string{"qso_date", "time_on", "band", "mode", "rst_sent"},
-		Footer: "{qso.qsl_msg}",
+		// PSE/TNX stamp (auto: TNX if a QSL was received, else PSE QSL) leads the
+		// message. {qso.pse_tnx} is a normal token — it can be moved to its own
+		// element anywhere on the card in the designer.
+		Footer: "{qso.pse_tnx}   {qso.qsl_msg}",
 	}
 	box.Y = cardH - box.H - 110
 	if zone.y+zone.h/2 > cardH/2 {