refactor: Enhance unique constraint validation across data operations

- Integrated `TableManagementService` to validate unique constraints before insert, update, and upsert actions in various controllers, including `dataflowExecutionController`, `dynamicFormController`, and `tableManagementController`.
- Improved error handling in `errorHandler` to provide detailed messages indicating which field has a unique constraint violation.
- Updated the `formatPgError` utility to extract and display specific column labels for unique constraint violations, enhancing user feedback.
- Adjusted the table schema retrieval to include company-specific nullable and unique constraints, ensuring accurate representation of database rules.

These changes improve data integrity by preventing duplicate entries and enhance user experience through clearer error messages related to unique constraints.

backend-node/src/services/multiTableExcelService.ts

@@ -970,10 +970,11 @@ class MultiTableExcelService {
     const result = await pool.query(
       `SELECT
          c.column_name,
-         c.is_nullable,
+         c.is_nullable AS db_is_nullable,
          c.column_default,
          COALESCE(ttc.column_label, cl.column_label) AS column_label,
-         COALESCE(ttc.reference_table, cl.reference_table) AS reference_table
+         COALESCE(ttc.reference_table, cl.reference_table) AS reference_table,
+         COALESCE(ttc.is_nullable, cl.is_nullable) AS ttc_is_nullable
        FROM information_schema.columns c
        LEFT JOIN table_type_columns cl
          ON c.table_name = cl.table_name AND c.column_name = cl.column_name AND cl.company_code = '*'
@@ -991,13 +992,13 @@ class MultiTableExcelService {
       // 시스템 컬럼 제외
       if (MultiTableExcelService.SYSTEM_COLUMNS.has(colName)) continue;
 
-      // FK 컬럼 제외 (reference_table이 있는 컬럼 = 다른 테이블의 PK를 참조)
-      // 단, 비즈니스적으로 의미 있는 FK는 남길 수 있으므로,
-      // _id로 끝나면서 reference_table이 있는 경우만 제외
+      // FK 컬럼 제외
       if (row.reference_table && colName.endsWith("_id")) continue;
 
       const hasDefault = row.column_default !== null;
-      const isNullable = row.is_nullable === "YES";
+      const dbNullable = row.db_is_nullable === "YES";
+      const ttcNotNull = row.ttc_is_nullable === "N";
+      const isNullable = ttcNotNull ? false : dbNullable;
       const isRequired = !isNullable && !hasDefault;
 
       columns.push({