feat: ESC/POS 영수증 프린터로 특이사항 인쇄 기능

- pos_printer.py: ESC/POS 유틸리티 (192.168.0.174:9100)
- POST /api/print/cusetc API 추가
- admin.html: 특이사항 옆 [🖨️ 인쇄] 버튼 추가
- EUC-KR 인코딩으로 한글 지원

backend/templates/admin.html

@@ -943,6 +943,34 @@
             const editBtn = document.querySelector('#cusetc-view').parentElement.querySelector('button');
             if (editBtn) editBtn.style.display = 'inline-block';
         }
+        
+        // 특이사항 인쇄
+        async function printCusetc(customerName, cusetc, phone) {
+            if (!confirm(`${customerName}님의 특이사항을 인쇄하시겠습니까?`)) {
+                return;
+            }
+            
+            try {
+                const res = await fetch('/api/print/cusetc', {
+                    method: 'POST',
+                    headers: { 'Content-Type': 'application/json' },
+                    body: JSON.stringify({
+                        customer_name: customerName,
+                        cusetc: cusetc,
+                        phone: phone
+                    })
+                });
+                const data = await res.json();
+                
+                if (data.success) {
+                    alert('🖨️ ' + data.message);
+                } else {
+                    alert('❌ 인쇄 실패: ' + (data.error || '알 수 없는 오류'));
+                }
+            } catch (err) {
+                alert('❌ 오류: ' + err.message);
+            }
+        }
 
         function renderUserDetail(data) {
             // 전역 변수에 데이터 저장
@@ -987,6 +1015,7 @@
                             <div style="display: flex; align-items: center; gap: 8px; margin-bottom: 6px;">
                                 <span style="color: #d97706; font-size: 13px;">⚠️ 특이사항</span>
                                 <button onclick="editCusetc('${data.pos_customer.cuscode}', this)" style="background: none; border: 1px solid #d97706; color: #d97706; font-size: 11px; padding: 2px 8px; border-radius: 4px; cursor: pointer;">✏️ 수정</button>
+                                ${data.pos_customer.cusetc ? `<button onclick="printCusetc('${data.pos_customer.name}', '${(data.pos_customer.cusetc || '').replace(/'/g, "\\'")}', '${user.phone || ''}')" style="background: none; border: 1px solid #6b7280; color: #6b7280; font-size: 11px; padding: 2px 8px; border-radius: 4px; cursor: pointer;">🖨️ 인쇄</button>` : ''}
                             </div>
                             <div id="cusetc-view" onclick="toggleCusetc(this)" style="color: #92400e; font-size: 14px; font-weight: 500; cursor: ${(data.pos_customer.cusetc || '').length > 30 ? 'pointer' : 'default'}; ${(data.pos_customer.cusetc || '').length > 30 ? 'max-height: 40px; overflow: hidden;' : ''}" title="${(data.pos_customer.cusetc || '').length > 30 ? '클릭하여 펼치기' : ''}">
                                 ${data.pos_customer.cusetc || '<span style="color: #9ca3af; font-weight: normal;">없음</span>'}