feat(bulk): My DXCC / My CQ zone / My ITU zone

The My-station group covered nineteen fields and not the three numeric ones.
They take their own integer path rather than the generic text setter: the
columns are nullable integers, and while SQLite would coerce '14' quietly, a
shared MySQL logbook would not — and empty must become NULL, never ''. Bounds
checked (DXCC <1000, CQ 1-40, ITU 1-90) so a slip cannot stamp zone 400 across
a thousand rows.

app.go

@@ -6938,6 +6938,28 @@ func (a *App) BulkUpdateField(ids []int64, field, value string) (int64, error) {
 	if field == "freq" {
 		return a.bulkSetFrequency(ids, value)
 	}
+	// The station-side numbers. Bounded so a slip cannot stamp CQ zone 400 on a
+	// thousand rows: DXCC entities stop short of 1000, CQ zones at 40, ITU at 90.
+	// Empty clears (NULL).
+	if field == "my_dxcc" || field == "my_cq_zone" || field == "my_itu_zone" {
+		var vp *int
+		if t := strings.TrimSpace(value); t != "" {
+			v, err := strconv.Atoi(t)
+			max := map[string]int{"my_dxcc": 999, "my_cq_zone": 40, "my_itu_zone": 90}[field]
+			if err != nil || v < 1 || v > max {
+				return 0, fmt.Errorf("%s must be a number between 1 and %d (empty to clear)", field, max)
+			}
+			vp = &v
+		}
+		n, err := a.qso.BulkSetIntField(a.ctx, ids, field, vp)
+		if err != nil {
+			return 0, err
+		}
+		if n > 0 {
+			a.invalidateAwardStats()
+		}
+		return n, nil
+	}
 	// Some ADIF fields have no promoted column and live in extras_json
 	// (OWNER_CALLSIGN) — those take the JSON path so the rest of the extras on
 	// each QSO survive the edit.