refactor: POP 그리드 시스템 명칭 통일 + Dead Code 제거

V5→V6 전환 과정에서 누적된 버전 접미사, 미사용 함수, 레거시 잔재를
정리하여 코드 관리성을 확보한다. 14개 파일 수정, 365줄 순감.
[타입 리네이밍] (14개 파일)
- PopLayoutDataV5 → PopLayoutData
- PopComponentDefinitionV5 → PopComponentDefinition
- PopGlobalSettingsV5 → PopGlobalSettings
- PopModeOverrideV5 → PopModeOverride
- createEmptyPopLayoutV5 → createEmptyLayout
- isV5Layout → isPopLayout
- addComponentToV5Layout → addComponentToLayout
- createComponentDefinitionV5 → createComponentDefinition
- 구 이름은 deprecated 별칭으로 유지 (하위 호환)
[Dead Code 삭제] (gridUtils.ts -350줄)
- getAdjustedBreakpoint, convertPositionToMode, isOutOfBounds,
  mouseToGridPosition, gridToPixelPosition, isValidPosition,
  clampPosition, autoLayoutComponents (전부 외부 사용 0건)
- needsReview + ReviewPanel/ReviewItem (항상 false, 미사용)
- getEffectiveComponentPosition export → 내부 함수로 전환
[레거시 로더 분리] (신규 legacyLoader.ts)
- convertV5LayoutToV6 → loadLegacyLayout (legacyLoader.ts)
- V5 변환 상수/함수를 gridUtils에서 분리
[주석 정리]
- "v5 그리드" → "POP 블록 그리드"
- "하위 호환용" → "뷰포트 프리셋" / "레이아웃 설정용"
- 파일 헤더, 섹션 구분, 함수 JSDoc 정리
기능 변경 0건. DB 변경 0건. 백엔드 변경 0건.

frontend/lib/registry/pop-components/pop-card-list-v2/PopCardListV2Component.tsx

@@ -49,8 +49,8 @@ import { usePopEvent } from "@/hooks/pop/usePopEvent";
 import { useCartSync } from "@/hooks/pop/useCartSync";
 import { NumberInputModal } from "../pop-card-list/NumberInputModal";
 import { renderCellV2 } from "./cell-renderers";
-import type { PopLayoutDataV5 } from "@/components/pop/designer/types/pop-layout";
-import { isV5Layout, detectGridMode } from "@/components/pop/designer/types/pop-layout";
+import type { PopLayoutData } from "@/components/pop/designer/types/pop-layout";
+import { isPopLayout, detectGridMode } from "@/components/pop/designer/types/pop-layout";
 import dynamic from "next/dynamic";
 const PopViewerWithModals = dynamic(() => import("@/components/pop/viewer/PopViewerWithModals"), { ssr: false });
 
@@ -216,7 +216,7 @@ export function PopCardListV2Component({
 
   // ===== 모달 열기 (POP 화면) =====
   const [popModalOpen, setPopModalOpen] = useState(false);
-  const [popModalLayout, setPopModalLayout] = useState<PopLayoutDataV5 | null>(null);
+  const [popModalLayout, setPopModalLayout] = useState<PopLayoutData | null>(null);
   const [popModalScreenId, setPopModalScreenId] = useState<string>("");
   const [popModalRow, setPopModalRow] = useState<RowData | null>(null);
 
@@ -228,7 +228,7 @@ export function PopCardListV2Component({
         return;
       }
       const popLayout = await screenApi.getLayoutPop(sid);
-      if (popLayout && isV5Layout(popLayout)) {
+      if (popLayout && isPopLayout(popLayout)) {
         setPopModalLayout(popLayout);
         setPopModalScreenId(String(sid));
         setPopModalRow(row);

frontend/lib/registry/pop-components/pop-scanner.tsx

@@ -19,7 +19,7 @@ import { usePopEvent } from "@/hooks/pop/usePopEvent";
 import { BarcodeScanModal } from "@/components/common/BarcodeScanModal";
 import type {
   PopDataConnection,
-  PopComponentDefinitionV5,
+  PopComponentDefinition,
 } from "@/components/pop/designer/types/pop-layout";
 
 // ========================================
@@ -99,7 +99,7 @@ function parseScanResult(
 function getConnectedFields(
   componentId?: string,
   connections?: PopDataConnection[],
-  allComponents?: PopComponentDefinitionV5[],
+  allComponents?: PopComponentDefinition[],
 ): ConnectedFieldInfo[] {
   if (!componentId || !connections || !allComponents) return [];
 
@@ -308,7 +308,7 @@ const PARSE_MODE_LABELS: Record<string, string> = {
 interface PopScannerConfigPanelProps {
   config: PopScannerConfig;
   onUpdate: (config: PopScannerConfig) => void;
-  allComponents?: PopComponentDefinitionV5[];
+  allComponents?: PopComponentDefinition[];
   connections?: PopDataConnection[];
   componentId?: string;
 }

frontend/lib/registry/pop-components/pop-search/PopSearchConfig.tsx

@@ -72,7 +72,7 @@ const DEFAULT_CONFIG: PopSearchConfig = {
 interface ConfigPanelProps {
   config: PopSearchConfig | undefined;
   onUpdate: (config: PopSearchConfig) => void;
-  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinitionV5[];
+  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinition[];
   connections?: import("@/components/pop/designer/types/pop-layout").PopDataConnection[];
   componentId?: string;
 }
@@ -151,7 +151,7 @@ export function PopSearchConfigPanel({ config, onUpdate, allComponents, connecti
 interface StepProps {
   cfg: PopSearchConfig;
   update: (partial: Partial<PopSearchConfig>) => void;
-  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinitionV5[];
+  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinition[];
   connections?: import("@/components/pop/designer/types/pop-layout").PopDataConnection[];
   componentId?: string;
 }
@@ -268,7 +268,7 @@ interface FilterConnectionSectionProps {
   update: (partial: Partial<PopSearchConfig>) => void;
   showFieldName: boolean;
   fixedFilterMode?: SearchFilterMode;
-  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinitionV5[];
+  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinition[];
   connections?: import("@/components/pop/designer/types/pop-layout").PopDataConnection[];
   componentId?: string;
 }
@@ -284,7 +284,7 @@ interface ConnectedComponentInfo {
 function getConnectedComponentInfo(
   componentId?: string,
   connections?: import("@/components/pop/designer/types/pop-layout").PopDataConnection[],
-  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinitionV5[],
+  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinition[],
 ): ConnectedComponentInfo {
   const empty: ConnectedComponentInfo = { tableNames: [], displayedColumns: new Set() };
   if (!componentId || !connections || !allComponents) return empty;

frontend/lib/registry/pop-components/pop-status-bar/PopStatusBarConfig.tsx

@@ -22,7 +22,7 @@ import { DEFAULT_STATUS_BAR_CONFIG, STATUS_CHIP_STYLE_LABELS } from "./types";
 interface ConfigPanelProps {
   config: StatusBarConfig | undefined;
   onUpdate: (config: StatusBarConfig) => void;
-  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinitionV5[];
+  allComponents?: import("@/components/pop/designer/types/pop-layout").PopComponentDefinition[];
   connections?: import("@/components/pop/designer/types/pop-layout").PopDataConnection[];
   componentId?: string;
 }