feat(hamlog): read confirmations back from a HAMLOG.online ADIF

Their agent protocol has no download verb, so the return path is a file
exported from their site. Running that file through the ordinary ADIF
import is the wrong tool and does real damage: it matches on callsign +
UTC minute + band + mode, their export is rebuilt from their own
database and rarely agrees to the minute, and 'update duplicates' then
inserts everything that failed to match -- several hundred copies of
contacts already in the log.

This path matches only. It stamps the confirmation on QSOs it finds,
falls back to the mode-CLASS key for the modes their export renames, and
REPORTS what it could not match instead of adding it: an unmatched
confirmation is a question about the log, not a contact to create.

Also logs and reports how many rows a delete actually removed -- silence
there made a delete that did nothing indistinguishable from one that
worked.

frontend/src/App.tsx

@@ -4297,8 +4297,14 @@ export default function App() {
     if (deletingIds.length === 0) return;
     const ids = deletingIds;
     try {
-      if (ids.length === 1) await DeleteQSO(ids[0]);
-      else await DeleteQSOs(ids as any);
+      // Report what was actually removed rather than assuming it matched what
+      // was asked: a delete that silently removes nothing looks exactly like one
+      // that worked, since the rows leave the grid when it reloads either way.
+      if (ids.length === 1) { await DeleteQSO(ids[0]); showToast(t('toast.deletedOne')); }
+      else {
+        const n = await DeleteQSOs(ids as any);
+        showToast(t('toast.deletedN', { n: Number(n ?? 0), asked: ids.length }));
+      }
       setDeletingIds([]);
       setSelectedId(null);
       setSelectedIds([]);