feat(copy): 복사 항목이 없는 부재(교량받침·기둥)에서는 속성 복사 패널을 숨김

- hasCopyItems 추가, 테스트 2건 (코핑·확대기초·지반은 표시, 교량받침·기둥은 숨김)
- "이 부재는 복사 항목이 없습니다" 문구 제거
- 대응표는 그대로 두어 항목이 생기면 자동으로 다시 표시

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

src/core/copy-targets.ts

@@ -39,6 +39,11 @@ export const MEMBER_COPY_ITEMS: Record<MemberId, CopyItem[]> = {
   ground: ['ground-position'],
 };
 
+/** Whether the 속성 복사 panel is shown for the 부재: only when it has copy items. */
+export function hasCopyItems(member: MemberId): boolean {
+  return copyItemsFor(member).length > 0;
+}
+
 /** The copy items for the selected 부재. */
 export function copyItemsFor(member: MemberId): CopyItem[] {
   return MEMBER_COPY_ITEMS[member];

src/main.ts

@@ -9,7 +9,7 @@ import { buildTemplateWorkbook } from './core/template';
 import { EDITABLE_FIELDS, FIELD_LABELS, overrideKeys, pendingKeys, revertDraft, type EditableKey, type PierValues } from './core/changes';
 import { adjustRow, layoutText, resolveRowCounts, rowLayout, totalPiles } from './core/piles';
 import { applyCopy, COPY_ITEMS, planCopy, type CopyItem } from './core/copy';
-import { copyCandidates, copyItemsFor, copyItemsWithOverrides, selectedTargets, type CopyCandidate } from './core/copy-targets';
+import { copyCandidates, copyItemsFor, copyItemsWithOverrides, hasCopyItems, selectedTargets, type CopyCandidate } from './core/copy-targets';
 import { pileGeometry } from './core/geometry';
 import { rebarSummary, type RebarRow } from './core/rebar/summary';
 import { shearSegments } from './core/rebar/coping';
@@ -678,7 +678,8 @@ function renderCopyItems(): void {
     label.append(check, document.createTextNode(COPY_ITEMS[item].label));
     box.appendChild(label);
   }
-  $('cp-none').hidden = items.length > 0;
+  // The panel is hidden for a 부재 without copy items (교량받침·기둥 are 예정).
+  $('copy-panel').hidden = !hasCopyItems(state.member);
 }
 
 function renderCopyTargets(): void {