feat(etl): add core ETL pipeline interfaces

Add the four core interfaces for the ETL pipeline:
- IImportSource: defines data sources for reading
- IDataTransformer: defines data transformation layer
- IImportDestination: defines data write destinations
- IScriptRunner: defines script execution capability

NEW/src/JdeScoping.DataSync/Etl/Contracts/IDataTransformer.cs

@@ -0,0 +1,21 @@
+using System.Data;
+
+namespace JdeScoping.DataSync.Etl.Contracts;
+
+/// <summary>
+/// Defines a transformer that can modify or enhance data during the ETL process.
+/// </summary>
+public interface IDataTransformer
+{
+    /// <summary>
+    /// Transforms the source data reader into a new data reader with modifications applied.
+    /// </summary>
+    /// <param name="source">The source data reader to transform.</param>
+    /// <returns>A new IDataReader with transformations applied.</returns>
+    IDataReader Transform(IDataReader source);
+
+    /// <summary>
+    /// Gets the name of this transformer for logging and identification.
+    /// </summary>
+    string TransformerName { get; }
+}

NEW/src/JdeScoping.DataSync/Etl/Contracts/IImportDestination.cs

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+using System.Data;
+using JdeScoping.DataSync.Etl.Results;
+
+namespace JdeScoping.DataSync.Etl.Contracts;
+
+/// <summary>
+/// Defines a destination to which data can be written during import operations.
+/// </summary>
+public interface IImportDestination
+{
+    /// <summary>
+    /// Writes data from the source reader to the destination asynchronously.
+    /// </summary>
+    /// <param name="source">The data reader containing the data to write.</param>
+    /// <param name="cancellationToken">Token to cancel the operation.</param>
+    /// <returns>A result containing statistics about the write operation.</returns>
+    Task<DestinationResult> WriteAsync(
+        IDataReader source,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets the name of this destination for logging and identification.
+    /// </summary>
+    string DestinationName { get; }
+}

NEW/src/JdeScoping.DataSync/Etl/Contracts/IImportSource.cs

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+using System.Data;
+
+namespace JdeScoping.DataSync.Etl.Contracts;
+
+/// <summary>
+/// Defines a source from which data can be read for import operations.
+/// </summary>
+public interface IImportSource : IAsyncDisposable
+{
+    /// <summary>
+    /// Reads data from the source asynchronously.
+    /// </summary>
+    /// <param name="cancellationToken">Token to cancel the operation.</param>
+    /// <returns>An IDataReader providing access to the source data.</returns>
+    Task<IDataReader> ReadDataAsync(CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets the name of this data source for logging and identification.
+    /// </summary>
+    string SourceName { get; }
+}

NEW/src/JdeScoping.DataSync/Etl/Contracts/IScriptRunner.cs

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+namespace JdeScoping.DataSync.Etl.Contracts;
+
+/// <summary>
+/// Defines a runner that can execute scripts as part of the ETL process.
+/// </summary>
+public interface IScriptRunner
+{
+    /// <summary>
+    /// Executes the script asynchronously.
+    /// </summary>
+    /// <param name="cancellationToken">Token to cancel the operation.</param>
+    Task ExecuteAsync(CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets the name of this script for logging and identification.
+    /// </summary>
+    string ScriptName { get; }
+}