feat: printer duplicate copies setting (Feature 1)

- Add `duplicates` column (0-9) to printers table via migration
- Print loop repeats job 1+duplicates times per printer zone
- PrinterForm in Settings > Print now has ΑΝΤΙΓΡΑΦΑ (0-9) field
- PrinterRow shows amber badge when duplicates > 0

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

manager_dashboard/src/pages/Settings/tabs/PrintFontsTab.jsx

@@ -637,7 +637,7 @@ function BeepSection({ beepEnabled, beepPattern, onChange, isPending, printers }
 // ── Printers section ───────────────────────────────────────────────────────
 
 const PROTOCOLS = [{ value: 'escpos_tcp', label: 'ESC/POS TCP (standard)' }]
-const EMPTY_FORM = { name: '', ip_address: '', port: 9100, protocol: 'escpos_tcp', line_width: 48, is_active: true }
+const EMPTY_FORM = { name: '', ip_address: '', port: 9100, protocol: 'escpos_tcp', line_width: 48, is_active: true, duplicates: 0 }
 
 function PrinterForm({ initial, onSave, onCancel, isPending }) {
   const [form, setForm] = useState(initial ?? EMPTY_FORM)
@@ -674,6 +674,11 @@ function PrinterForm({ initial, onSave, onCancel, isPending }) {
         <input value={form.line_width} onChange={e => set('line_width', parseInt(e.target.value) || 48)}
           type="number" min={20} max={80} style={inputStyle} />
       </div>
+      <div style={{ display: 'flex', flexDirection: 'column', gap: 4, flex: '0 0 90px' }}>
+        <label style={{ fontSize: 11, fontWeight: 600, color: '#6b7280' }}>ΑΝΤΙΓΡΑΦΑ</label>
+        <input value={form.duplicates ?? 0} onChange={e => set('duplicates', Math.max(0, Math.min(9, parseInt(e.target.value) || 0)))}
+          type="number" min={0} max={9} style={inputStyle} title="0 = μία εκτύπωση, 1 = δύο κ.ο.κ." />
+      </div>
       <div style={{ display: 'flex', gap: 8, alignItems: 'center', paddingBottom: 2 }}>
         <button onClick={() => onSave(form)} disabled={isPending || !form.name.trim() || !form.ip_address.trim()}
           style={btnPrimary}>Αποθήκευση</button>
@@ -739,6 +744,11 @@ function PrinterRow({ printer, onEdit, onDelete, onTest, onToggle, testPending }
         </span>
         <span style={{ fontSize: 11, color: '#9ca3af', marginLeft: 6 }}>— {printer.protocol}</span>
         <span style={{ fontSize: 11, color: '#9ca3af', marginLeft: 6 }}>— {printer.line_width ?? 48} χαρ.</span>
+        {(printer.duplicates ?? 0) > 0 && (
+          <span style={{ fontSize: 11, color: '#f59e0b', fontWeight: 700, marginLeft: 6 }}>
+            — x{(printer.duplicates ?? 0) + 1} αντ.
+          </span>
+        )}
       </div>
 
       <span style={{