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/Configuration/PipelinesRoot.cs

@@ -5,7 +5,9 @@ public record PipelinesRoot(
     ScheduleDefaults? ScheduleDefaults,  // Optional - defaults applied if missing
     Dictionary<string, PipelineConfig> Pipelines)
 {
+    /// <summary>Gets the effective pipeline settings, using defaults if not specified.</summary>
     public PipelineSettings EffectiveSettings => Settings ?? new PipelineSettings();
+    /// <summary>Gets the effective schedule defaults, using defaults if not specified.</summary>
     public ScheduleDefaults EffectiveScheduleDefaults => ScheduleDefaults ?? new ScheduleDefaults();
 }
 

NEW/src/JdeScoping.DataSync/Configuration/ScheduleConfig.cs

@@ -33,6 +33,7 @@ public record ScheduleConfig
     /// <summary>
     /// Merges this config with defaults. Non-null/non-default values in this config override defaults.
     /// </summary>
+    /// <param name="defaults">The default configuration to merge with.</param>
     public ScheduleConfig MergeWith(ScheduleConfig defaults)
     {
         return new ScheduleConfig
@@ -92,7 +93,18 @@ public record ScheduleDefaults
 /// </summary>
 public record PipelineSchedules
 {
+    /// <summary>
+    /// Gets or initializes the Mass schedule configuration override.
+    /// </summary>
     public ScheduleConfig? Mass { get; init; }
+
+    /// <summary>
+    /// Gets or initializes the Daily schedule configuration override.
+    /// </summary>
     public ScheduleConfig? Daily { get; init; }
+
+    /// <summary>
+    /// Gets or initializes the Hourly schedule configuration override.
+    /// </summary>
     public ScheduleConfig? Hourly { get; init; }
 }