refactor(B06): 700줄 초과 파일 분리 — Router·Cross_View·Section_View·Style

- B06_Section_Router.py(824) → Router_Design.py(139) 분리
- Cross_View → Cross_View_Metrics.ts(75) 분리
- Cross_Design → Cross_Design_Surface.ts(54) 분리
- Section_View → Section_View_Panel.ts(53) 분리
- Page → Page_Common.ts(15) 분리
- Style_Cross.css → Style_Cross_Controls.css(174) 분리
- B06_Section/ 전체 700줄 초과 0건

검증: tsc --noEmit 통과 · ruff check 통과(import 정렬·포맷 적용) ·
prettier 적용 · pytest tmp/tests/ 148 passed, 7 skipped.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

B06_Section/B06_Section_UI_Cross_Design.ts

@@ -24,6 +24,10 @@ import type {
   SectionMode,
   SectionSample,
 } from "./B06_Section_Api_Fetch";
+export {
+  appendPavementOverlay,
+  appendRockBoundaryOverlay,
+} from "./B06_Section_UI_Cross_Design_Surface";
 
 const SVG_NS = "http://www.w3.org/2000/svg";
 
@@ -638,53 +642,3 @@ export function appendCrossDesignOverlay(
  * 리핑암·발파암 지반에서만 호출한다. offsetM 음수 = 하향.
  * 무효 샘플 구간은 지반선과 동일하게 선을 끊어 그린다.
  */
-export function appendRockBoundaryOverlay(
-  svg: SVGElement,
-  groundSamples: Array<{ offset_m?: number; elevation_m?: number | null; valid: boolean }>,
-  offsetM: number,
-  x: (offset: number) => number,
-  toDisplayY: (elevation: number) => number,
-): void {
-  const segments: string[][] = [];
-  let current: string[] = [];
-  for (const sample of groundSamples) {
-    const elevation = sample.elevation_m;
-    if (sample.valid === false || elevation === null || !Number.isFinite(elevation ?? NaN)) {
-      if (current.length > 1) segments.push(current);
-      current = [];
-      continue;
-    }
-    current.push(`${x(sample.offset_m ?? 0)},${toDisplayY((elevation as number) + offsetM)}`);
-  }
-  if (current.length > 1) segments.push(current);
-  for (const points of segments) {
-    const polyline = document.createElementNS(SVG_NS, "polyline");
-    polyline.setAttribute("points", points.join(" "));
-    polyline.setAttribute("class", "b06-chart__rock-boundary");
-    svg.append(polyline);
-  }
-}
-
-/** 포장 측점의 노면 포장층 박스를 겹쳐 그린다 (노면 양 끝점 기준, 두께만큼 하향). */
-export function appendPavementOverlay(
-  svg: SVGElement,
-  design: CrossDesign,
-  x: (offset: number) => number,
-  toDisplayY: (elevation: number) => number,
-): void {
-  // 포장은 차도(노견 제외)만 덮는다(D-5). 구 데이터 폴백으로 road_edges를 쓴다.
-  const edges = design.carriageway_edges ?? design.road_edges;
-  if (!design.paved || !edges) return;
-  const thickness = design.pavement_thickness_m ?? 0.2;
-  const { left, right } = edges;
-  const points = [
-    `${x(left.offset_m)},${toDisplayY(left.elevation_m)}`,
-    `${x(right.offset_m)},${toDisplayY(right.elevation_m)}`,
-    `${x(right.offset_m)},${toDisplayY(right.elevation_m - thickness)}`,
-    `${x(left.offset_m)},${toDisplayY(left.elevation_m - thickness)}`,
-  ];
-  const polygon = document.createElementNS(SVG_NS, "polygon");
-  polygon.setAttribute("points", points.join(" "));
-  polygon.setAttribute("class", "b06-chart__pavement");
-  svg.append(polygon);
-}