feat: PMR 라벨 미리보기 기능

- /pmr/api/label/preview: PIL 렌더링 → Base64 이미지
- 미리보기 버튼 + 모달 추가
- 29mm 용지 기준 라벨 이미지 생성

backend/templates/pmr.html

@@ -295,8 +295,21 @@
             </div>
             <div class="action-bar" id="actionBar" style="display:none;">
                 <button class="btn btn-secondary" onclick="selectAll()">전체 선택</button>
+                <button class="btn btn-secondary" onclick="previewLabels()" style="background:#3b82f6;color:#fff;">👁️ 미리보기</button>
                 <button class="btn btn-primary" onclick="printLabels()">🖨️ 라벨 인쇄</button>
             </div>
+            
+            <!-- 미리보기 모달 -->
+            <div id="previewModal" style="display:none;position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(0,0,0,0.7);z-index:1000;overflow-y:auto;">
+                <div style="max-width:400px;margin:50px auto;background:#fff;border-radius:12px;padding:20px;">
+                    <div style="display:flex;justify-content:space-between;align-items:center;margin-bottom:15px;">
+                        <h3 style="margin:0;color:#4c1d95;">🏷️ 라벨 미리보기</h3>
+                        <button onclick="closePreview()" style="background:none;border:none;font-size:1.5rem;cursor:pointer;">×</button>
+                    </div>
+                    <div id="previewContent" style="display:flex;flex-direction:column;gap:15px;align-items:center;">
+                    </div>
+                </div>
+            </div>
         </div>
     </div>
 
@@ -466,6 +479,65 @@
             if (checkAll) checkAll.checked = true;
         }
         
+        // 라벨 미리보기
+        async function previewLabels() {
+            const rows = document.querySelectorAll('.med-check:checked');
+            if (rows.length === 0) {
+                alert('미리보기할 약품을 선택하세요');
+                return;
+            }
+            
+            const container = document.getElementById('previewContent');
+            container.innerHTML = '<div class="loading"><div class="spinner"></div></div>';
+            document.getElementById('previewModal').style.display = 'block';
+            
+            // 현재 선택된 환자명
+            const patientName = document.getElementById('detailName').textContent;
+            
+            container.innerHTML = '';
+            
+            for (const checkbox of rows) {
+                const tr = checkbox.closest('tr');
+                const medName = tr.querySelector('.med-name')?.textContent || '';
+                const dosage = parseFloat(tr.cells[3]?.querySelector('.med-dosage')?.textContent) || 0;
+                const frequency = parseInt(tr.cells[4]?.textContent) || 0;
+                const duration = parseInt(tr.cells[5]?.textContent) || 0;
+                
+                try {
+                    const res = await fetch('/pmr/api/label/preview', {
+                        method: 'POST',
+                        headers: {'Content-Type': 'application/json'},
+                        body: JSON.stringify({
+                            patient_name: patientName,
+                            med_name: medName,
+                            dosage: dosage,
+                            frequency: frequency,
+                            duration: duration,
+                            unit: '정'
+                        })
+                    });
+                    const data = await res.json();
+                    
+                    if (data.success) {
+                        const img = document.createElement('img');
+                        img.src = data.image;
+                        img.style.cssText = 'max-width:100%;border:1px solid #ddd;border-radius:8px;';
+                        container.appendChild(img);
+                    }
+                } catch (err) {
+                    console.error('Preview error:', err);
+                }
+            }
+            
+            if (container.children.length === 0) {
+                container.innerHTML = '<p style="color:#999;">미리보기 생성 실패</p>';
+            }
+        }
+        
+        function closePreview() {
+            document.getElementById('previewModal').style.display = 'none';
+        }
+        
         // 라벨 인쇄 (TODO: 구현)
         function printLabels() {
             const selected = Array.from(document.querySelectorAll('.med-check:checked')).map(c => c.dataset.code);