docs: add XML documentation and ConfigManager implementation plans

Add comprehensive XML documentation (param/returns tags) across 132 source
files to improve IntelliSense and API discoverability. Include ConfigManager
design documents and implementation plans for phases 1-9.

NEW/src/JdeScoping.DataSync.Dev/Configuration/DevPipelinesRoot.cs

@@ -7,6 +7,9 @@ public record DevPipelinesRoot(
     DevPipelineSettings? Settings,
     Dictionary<string, DevPipelineConfig> Pipelines)
 {
+    /// <summary>
+    /// Gets the effective settings, using defaults if not specified.
+    /// </summary>
     public DevPipelineSettings EffectiveSettings => Settings ?? new DevPipelineSettings();
 }
 

NEW/src/JdeScoping.DataSync.Dev/DevEtlRegistry.cs

@@ -15,6 +15,12 @@ public class DevEtlRegistry
     private readonly string _cacheDirectory;
     private readonly ILogger<DevEtlRegistry>? _logger;
 
+    /// <summary>
+    /// Initializes a new instance of the DevEtlRegistry.
+    /// </summary>
+    /// <param name="pipelineFactory">The factory for creating ETL pipelines.</param>
+    /// <param name="cacheDirectory">The directory containing cached protobuf files.</param>
+    /// <param name="logger">Optional logger for recording ETL operations.</param>
     public DevEtlRegistry(
         IDevEtlPipelineFactory pipelineFactory,
         string cacheDirectory,
@@ -32,8 +38,16 @@ public class DevEtlRegistry
         _logger = logger;
     }
 
+    /// <summary>
+    /// Gets the list of available tables that can be loaded.
+    /// </summary>
     public IEnumerable<string> GetAvailableTables() => _pipelineFactory.GetAvailableTables();
 
+    /// <summary>
+    /// Runs the ETL pipeline for a single table.
+    /// </summary>
+    /// <param name="tableName">The name of the table to load.</param>
+    /// <param name="cancellationToken">The cancellation token.</param>
     public async Task<PipelineResult> RunAsync(string tableName, CancellationToken cancellationToken = default)
     {
         _logger?.LogInformation("Running dev ETL for {TableName}", tableName);
@@ -51,6 +65,10 @@ public class DevEtlRegistry
         return result;
     }
 
+    /// <summary>
+    /// Runs the ETL pipeline for all available tables sequentially.
+    /// </summary>
+    /// <param name="cancellationToken">The cancellation token.</param>
     public async Task<IReadOnlyList<PipelineResult>> RunAllAsync(CancellationToken cancellationToken = default)
     {
         var results = new List<PipelineResult>();

NEW/src/JdeScoping.DataSync.Dev/Services/DevEtlPipelineFactory.cs

@@ -31,6 +31,9 @@ public class DevEtlPipelineFactory : IDevEtlPipelineFactory
     /// <summary>
     /// Creates a new development pipeline factory.
     /// </summary>
+    /// <param name="connectionFactory">Factory for creating database connections.</param>
+    /// <param name="options">Configuration options for the development pipeline.</param>
+    /// <param name="logger">Logger for pipeline operations.</param>
     public DevEtlPipelineFactory(
         IDbConnectionFactory connectionFactory,
         IOptions<DevPipelineOptions> options,
@@ -49,6 +52,9 @@ public class DevEtlPipelineFactory : IDevEtlPipelineFactory
     /// <summary>
     /// Creates a new development pipeline factory with pre-loaded config (for testing).
     /// </summary>
+    /// <param name="connectionFactory">Factory for creating database connections.</param>
+    /// <param name="config">Pre-loaded pipeline configuration.</param>
+    /// <param name="logger">Logger for pipeline operations.</param>
     internal DevEtlPipelineFactory(
         IDbConnectionFactory connectionFactory,
         DevPipelinesRoot config,

NEW/src/JdeScoping.DataSync.Dev/Sources/ProtobufZstdFileSource.cs

@@ -26,8 +26,17 @@ public sealed class ProtobufZstdFileSource : IImportSource
     private BufferedStream? _bufferedStream;
     private IDataReader? _reader;
 
+    /// <summary>
+    /// The name of this source, including the file name.
+    /// </summary>
     public string SourceName => $"Protobuf:{Path.GetFileName(_filePath)}";
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ProtobufZstdFileSource"/> class.
+    /// </summary>
+    /// <param name="filePath">The path to the zstd-compressed protobuf file.</param>
+    /// <exception cref="ArgumentException">Thrown when filePath is null or empty.</exception>
+    /// <exception cref="FileNotFoundException">Thrown when the file does not exist.</exception>
     public ProtobufZstdFileSource(string filePath)
     {
         if (string.IsNullOrWhiteSpace(filePath))
@@ -39,6 +48,12 @@ public sealed class ProtobufZstdFileSource : IImportSource
         _filePath = filePath;
     }
 
+    /// <summary>
+    /// Reads and decompresses the protobuf file, returning an IDataReader for deserialization.
+    /// </summary>
+    /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>An IDataReader for reading the decompressed protobuf data.</returns>
+    /// <exception cref="InvalidOperationException">Thrown if ReadDataAsync has already been called.</exception>
     public async Task<IDataReader> ReadDataAsync(CancellationToken cancellationToken = default)
     {
         if (_fileStream != null)
@@ -85,6 +100,9 @@ public sealed class ProtobufZstdFileSource : IImportSource
         _fileStream = null;
     }
 
+    /// <summary>
+    /// Disposes of all unmanaged resources associated with this source.
+    /// </summary>
     public async ValueTask DisposeAsync()
     {
         if (_reader != null)