feat: Phase 2 - 성분코드 기반 투약주기/병용약 JOIN 구현

- component_guide 테이블 생성 (PostgreSQL)
- IC2030126 (메벤다졸+프라지퀸텔) 샘플 데이터 입력
- 미리보기 API: apc + component_guide LEFT JOIN
- 모달에 투약주기, 병용약 섹션 추가 (보라색/녹색 강조)

backend/templates/admin_products.html

@@ -1165,6 +1165,18 @@
                     <p style="margin:0;font-size:13px;line-height:1.7;color:#334155;white-space:pre-line;">${escapeHtml(info.precautions.substring(0, 800))}${info.precautions.length > 800 ? '...' : ''}</p>
                 </div>` : ''}
                 
+                ${info.dosing_interval ? `
+                <div style="margin-bottom:12px;background:#faf5ff;padding:12px;border-radius:8px;border:2px solid #c084fc;">
+                    <h5 style="margin:0 0 6px;color:#7c3aed;">▶ 투약 주기 ⭐</h5>
+                    <p style="margin:0;font-size:13px;line-height:1.7;color:#334155;white-space:pre-line;">${escapeHtml(info.dosing_interval)}</p>
+                </div>` : ''}
+                
+                ${info.companion_drugs ? `
+                <div style="margin-bottom:12px;background:#ecfdf5;padding:12px;border-radius:8px;border:2px solid #34d399;">
+                    <h5 style="margin:0 0 6px;color:#059669;">▶ 함께 투약 권장 💊</h5>
+                    <p style="margin:0;font-size:13px;line-height:1.7;color:#334155;">${escapeHtml(info.companion_drugs)}</p>
+                </div>` : ''}
+                
                 <div style="display:flex;gap:10px;margin-top:20px;">
                     <button onclick="document.getElementById('animalDrugModal').remove()" 
                             style="flex:1;padding:10px;border:1px solid #e2e8f0;background:#fff;border-radius:6px;cursor:pointer;">닫기</button>