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.Client/Models/ValidCombination.cs

@@ -6,21 +6,74 @@ namespace JdeScoping.Client.Models;
 /// </summary>
 public class ValidCombination
 {
+    /// <summary>
+    /// The unique identifier for this combination.
+    /// </summary>
     public int Id { get; private init; }
+
+    /// <summary>
+    /// The display name for this combination.
+    /// </summary>
     public string Name { get; private init; } = string.Empty;
+
+    /// <summary>
+    /// Whether the timespan filter is included in this combination.
+    /// </summary>
     public bool Timespan { get; private init; }
+
+    /// <summary>
+    /// Whether the work order filter is included in this combination.
+    /// </summary>
     public bool WorkOrder { get; private init; }
+
+    /// <summary>
+    /// Whether the item number filter is included in this combination.
+    /// </summary>
     public bool ItemNumber { get; private init; }
+
+    /// <summary>
+    /// Whether the profit center filter is included in this combination.
+    /// </summary>
     public bool ProfitCenter { get; private init; }
+
+    /// <summary>
+    /// Whether the work center filter is included in this combination.
+    /// </summary>
     public bool WorkCenter { get; private init; }
+
+    /// <summary>
+    /// Whether the component lot filter is included in this combination.
+    /// </summary>
     public bool ComponentLot { get; private init; }
+
+    /// <summary>
+    /// Whether the operator filter is included in this combination.
+    /// </summary>
     public bool Operator { get; private init; }
+
+    /// <summary>
+    /// Whether the item operation MIS filter is included in this combination.
+    /// </summary>
     public bool ItemOperationMis { get; private init; }
+
+    /// <summary>
+    /// Whether the extract MIS filter is included in this combination.
+    /// </summary>
     public bool ExtractMis { get; private init; }
 
     /// <summary>
     /// Checks if the given filter flags match this combination.
     /// </summary>
+    /// <param name="timespan">Whether timespan filter is enabled.</param>
+    /// <param name="workOrder">Whether work order filter is enabled.</param>
+    /// <param name="itemNumber">Whether item number filter is enabled.</param>
+    /// <param name="profitCenter">Whether profit center filter is enabled.</param>
+    /// <param name="workCenter">Whether work center filter is enabled.</param>
+    /// <param name="componentLot">Whether component lot filter is enabled.</param>
+    /// <param name="operator">Whether operator filter is enabled.</param>
+    /// <param name="itemOperationMis">Whether item operation MIS filter is enabled.</param>
+    /// <param name="extractMis">Whether extract MIS filter is enabled.</param>
+    /// <returns>True if all flags match this combination.</returns>
     public bool Matches(
         bool timespan,
         bool workOrder,