fix(qsl): separate the QSL manager from the routing method (#16)

QSL_VIA is the manager. QSL_SENT_VIA and QSL_RCVD_VIA are the ADIF "QSL Via"
enumeration — B bureau, D direct, E electronic, M manager (import-only) —
and say how a card travelled. OpsLog had one column for all three:

  - the import folded QSL_SENT_VIA into QSL_VIA whenever QSL_VIA was empty,
    which is exactly a Log4OM export (it defaults QSL_SENT_VIA to E), so
    OE6CLD saw "E" everywhere OpsLog shows the manager;
  - QSL_RCVD_VIA was listed in adifPromoted with no column behind it, so it
    was not stored, not kept among the extras, and not exported — dropped
    outright on import;
  - neither was ever written on export, so an import followed by an export
    destroyed both;
  - and OpsLog polluted the field itself: the QSL Manager panel wrote
    "Bureau" / "Direct" / "Electronic", in full words, into QSL_VIA.

Two columns added (migration 0027), carried through the five places a
promoted ADIF field has to touch, with round-trip tests pinning the reported
case. The QSL panel now offers Bureau / Direct / Electronic for each
direction and stores the enumeration; the manager field is labelled as the
manager and holds only that. M is kept when a file gives it and never
written back out.

Existing logs hold a mixture of the two in one column. The repair is offered,
not performed: the count is shown once per log with a plain question, and a
"no" is remembered. It moves only where QSL_SENT_VIA is still empty, and only
values that normalise to the enumeration — a manager is a callsign and can
never be one of those six words, which a test pins against real manager calls.

frontend/wailsjs/go/main/App.js

@@ -294,6 +294,10 @@ export function DismissAwardUpdate(arg1) {
   return window['go']['main']['App']['DismissAwardUpdate'](arg1);
 }
 
+export function DismissQSLViaRepair() {
+  return window['go']['main']['App']['DismissQSLViaRepair']();
+}
+
 export function DownloadAllReferenceLists() {
   return window['go']['main']['App']['DownloadAllReferenceLists']();
 }
@@ -1558,6 +1562,10 @@ export function QSLStylePresets() {
   return window['go']['main']['App']['QSLStylePresets']();
 }
 
+export function QSLViaRepairStatus() {
+  return window['go']['main']['App']['QSLViaRepairStatus']();
+}
+
 export function QSOAudioBegin() {
   return window['go']['main']['App']['QSOAudioBegin']();
 }
@@ -1634,6 +1642,10 @@ export function RenderEQSL(arg1, arg2) {
   return window['go']['main']['App']['RenderEQSL'](arg1, arg2);
 }
 
+export function RepairQSLVia() {
+  return window['go']['main']['App']['RepairQSLVia']();
+}
+
 export function ReplaceAwardReferences(arg1, arg2) {
   return window['go']['main']['App']['ReplaceAwardReferences'](arg1, arg2);
 }