feat: Implement entity join functionality in V2Repeater and configuration panel

- Added support for entity joins in the V2Repeater component, allowing for automatic resolution of foreign key references to display data from related tables.
- Introduced a new `resolveEntityJoins` function to handle the fetching and mapping of reference data based on configured entity joins.
- Enhanced the V2RepeaterConfigPanel to manage entity join configurations, including loading available columns and toggling join settings.
- Updated the data handling logic to incorporate mapping rules for incoming data, ensuring that only necessary fields are retained during processing.
- Improved user experience by providing clear logging and feedback during entity join resolution and data mapping operations.

frontend/lib/registry/components/split-panel-layout2/SplitPanelLayout2Component.tsx

@@ -642,6 +642,12 @@ export const SplitPanelLayout2Component: React.FC<SplitPanelLayout2ComponentProp
       }
     }
 
+    // 메인 레코드 ID 전달 (분할패널에서는 좌측 선택 항목이 메인 레코드)
+    const leftPkColumn = config.leftPanel?.primaryKeyColumn || "id";
+    if (selectedLeftItem?.[leftPkColumn]) {
+      initialData._mainRecordId = selectedLeftItem[leftPkColumn];
+    }
+
     // EditModal 열기 이벤트 발생
     const event = new CustomEvent("openEditModal", {
       detail: {
@@ -662,6 +668,7 @@ export const SplitPanelLayout2Component: React.FC<SplitPanelLayout2ComponentProp
   }, [
     config.rightPanel?.addModalScreenId,
     config.rightPanel?.addButtonLabel,
+    config.leftPanel?.primaryKeyColumn,
     config.dataTransferFields,
     selectedLeftItem,
     loadRightData,
@@ -718,6 +725,12 @@ export const SplitPanelLayout2Component: React.FC<SplitPanelLayout2ComponentProp
         }
       }
 
+      // 메인 레코드 ID 전달 (디테일 레코드의 id와 구분)
+      const editItemLeftPkColumn = config.leftPanel?.primaryKeyColumn || "id";
+      if (selectedLeftItem?.[editItemLeftPkColumn]) {
+        editData._mainRecordId = selectedLeftItem[editItemLeftPkColumn];
+      }
+
       // EditModal 열기 이벤트 발생 (수정 모드)
       const event = new CustomEvent("openEditModal", {
         detail: {
@@ -737,7 +750,7 @@ export const SplitPanelLayout2Component: React.FC<SplitPanelLayout2ComponentProp
       window.dispatchEvent(event);
       console.log("[SplitPanelLayout2] 우측 수정 모달 열기:", editData);
     },
-    [config.rightPanel?.editModalScreenId, config.rightPanel?.addModalScreenId, config.rightPanel?.mainTableForEdit, selectedLeftItem, loadRightData, loadLeftData],
+    [config.rightPanel?.editModalScreenId, config.rightPanel?.addModalScreenId, config.rightPanel?.mainTableForEdit, config.leftPanel?.primaryKeyColumn, selectedLeftItem, loadRightData, loadLeftData],
   );
 
   // 좌측 패널 수정 버튼 클릭
@@ -896,6 +909,12 @@ export const SplitPanelLayout2Component: React.FC<SplitPanelLayout2ComponentProp
               }
             }
 
+            // 메인 레코드 ID 전달 (분할패널에서는 좌측 선택 항목이 메인 레코드)
+            const addLeftPkColumn = config.leftPanel?.primaryKeyColumn || "id";
+            if (selectedLeftItem?.[addLeftPkColumn]) {
+              initialData._mainRecordId = selectedLeftItem[addLeftPkColumn];
+            }
+
             const event = new CustomEvent("openEditModal", {
               detail: {
                 screenId: btn.modalScreenId,
@@ -929,12 +948,19 @@ export const SplitPanelLayout2Component: React.FC<SplitPanelLayout2ComponentProp
                 return;
               }
 
+              // 메인 레코드 ID 전달 (디테일 레코드의 id와 구분)
+              const editLeftPkColumn = config.leftPanel?.primaryKeyColumn || "id";
+              const editData = { ...item };
+              if (selectedLeftItem?.[editLeftPkColumn]) {
+                editData._mainRecordId = selectedLeftItem[editLeftPkColumn];
+              }
+
               const event = new CustomEvent("openEditModal", {
                 detail: {
                   screenId: modalScreenId,
                   title: btn.label || "수정",
                   modalSize: "lg",
-                  editData: item,
+                  editData,
                   isCreateMode: false,
                   onSave: () => {
                     if (selectedLeftItem) {