feat: replace 2 m placeholder with station pattern table from the workbook (Task 5)

Source: RAG 지보패턴현황_20260918.xlsx, sheet 참고_지보패턴현황, 당진방향 table
(4+740..5+500, 42 contiguous rows). Lining pattern (M column) per station now
drives the lining colour and the viewer readout. Daesan table kept as reference
only (WL-4 there, not applied). Drawing patterns E-1, E-2, RP-2, WL-3 are in
neither table and stay [미확정].

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A5Cun3RHQKna9qxE6ybZ4A

viewer/index.html

@@ -121,7 +121,7 @@ renderer.domElement.addEventListener('pointerup', (e) => {
       const sta = M.first_station + ring * M.ring_step_m;
       const z = M.patterns.find((z) => sta >= z.from && sta < z.to);
       const km = Math.floor(sta / 1000), m = Math.round(sta % 1000);
-      extra = '\n측점: ' + km + '+' + String(m).padStart(3, '0') + '\n패턴: ' + (z ? z.pattern : '-') + ' (임의 배정, 실제 구간 아님)' + (M.lining_reference ? '\n라이닝 상세: ' + M.lining_reference.summary : '');
+      extra = '\n측점: ' + km + '+' + String(m).padStart(3, '0') + '\n패턴: ' + (z ? z.pattern : '-') + ' (엑셀 지보패턴표, 당진방향)' + (M.lining_reference ? '\n라이닝 상세: ' + M.lining_reference.summary : '');
     }
     info.textContent = (INFO[key] || key) + extra + '\n교차점: x=' + hit.point.x.toFixed(2) + ' y=' + hit.point.y.toFixed(2) + ' z=' + hit.point.z.toFixed(2) + ' (m, 모델 좌표)';
   }