feat: add DEX job common infrastructure

Add foundational types for DEX job execution:

Constants:
- ErrorAction enum (Ignore, Stop) for error handling strategy

DTOs:
- CheckQueryResult: check query execution result with ReturnValue
- MainQueryResult: main query execution result with ReturnValue

Interfaces:
- ISQLExecutor: abstraction for SQL query execution and DTO mapping

All types include comprehensive XML documentation

ECMJobRunner.Application/Common/Constants/ErrorAction.cs

@@ -0,0 +1,18 @@
+namespace ECMJobRunner.Application.Common.Constants
+{
+    /// <summary>
+    /// Defines actions to take when an error occurs during job execution
+    /// </summary>
+    public enum ErrorAction
+    {
+        /// <summary>
+        /// Ignore the error and continue execution
+        /// </summary>
+        Ignore,
+
+        /// <summary>
+        /// Stop execution and throw an exception
+        /// </summary>
+        Stop,
+    }
+}