feat: Station Control amp parity + all amps, Help→Send log to F4BPO, bulk-edit frequency, fix Cluster midnight sort

- Station Control: the amplifier panel is now the exact same card as the FlexRadio panel (extracted shared AmpCard: OPERATE/STANDBY, ON/OFF, power level, output-power bar, live FWD/ID/temp meters). Every configured amp gets its own card — no dropdown.
- Help → "Send log to F4BPO" (only when SMTP is configured): e-mails opslog.log + previous session + crash log to the developer. New email.SendFiles for multi-attachment.
- Bulk edit: new "Frequency (MHz)" field sets freq_hz AND recomputes band; out-of-band values rejected. Fixes a run logged on a stale/default freq after CAT dropped.
- Cluster: Time column sorted lexically on the HHMMZ string, so spots after 0000Z sorted below 2359Z and looked frozen at the UTC rollover. Now sorts by real arrival time.
- Also folds in the DVK auto-CQ/2-column layout and Station Control dashboard batch (changelog 0.20.10, EN+FR).

internal/qso/qso.go

@@ -792,6 +792,31 @@ func (r *Repo) BulkSetField(ctx context.Context, ids []int64, column, value stri
 	return n, nil
 }
 
+// BulkSetFrequency sets freq_hz AND band together on every listed QSO. Kept
+// separate from BulkSetField because frequency is numeric and must keep the band
+// consistent — the main use is fixing a batch that was logged on a stale/default
+// frequency after CAT dropped. freqHz "" is not allowed (caller validates).
+func (r *Repo) BulkSetFrequency(ctx context.Context, ids []int64, freqHz int64, band string) (int64, error) {
+	if len(ids) == 0 {
+		return 0, nil
+	}
+	ph := make([]string, len(ids))
+	args := make([]any, 0, len(ids)+3)
+	args = append(args, freqHz, band, db.NowISO())
+	for i, id := range ids {
+		ph[i] = "?"
+		args = append(args, id)
+	}
+	res, err := r.db.ExecContext(ctx,
+		`UPDATE qso SET freq_hz = ?, band = ?, updated_at = ? WHERE id IN (`+strings.Join(ph, ",")+`)`,
+		args...)
+	if err != nil {
+		return 0, fmt.Errorf("bulk set frequency: %w", err)
+	}
+	n, _ := res.RowsAffected()
+	return n, nil
+}
+
 // SetExtra merges ONE key into a QSO's extras JSON without rewriting the rest of
 // the row. A slow caller that only wants to stamp its own app field (e-mailing a
 // QSL card, saving a recording) must not do a full-row Update: the row it read may