feat(inventory): add Source to InventoryLoadConfig

Adds a `GrantSource Source { get; set; }` property (defaults to
`GrantSource.Unknown`) to `InventoryLoadConfig`. Plumbing-only — no
behavior change; callers that don't set `Source` get Unknown rows,
greppable via `acquire_type=0` in dev.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.Database/Services/Inventory/InventoryLoadConfig.cs

@@ -9,11 +9,23 @@ namespace SVSim.Database.Services.Inventory;
 /// Caller-supplied extra <c>.Include</c> chains on top of the canonical viewer-inventory query
 /// in <see cref="IInventoryService.BeginAsync"/>. Use to bring in extra collections needed by
 /// the calling controller (e.g. <c>MissionData</c>, <c>BuildDeckPurchases</c>).
+/// <para>
+/// Also carries the <see cref="Source"/> tag that <see cref="IInventoryTransaction.CommitAsync"/>
+/// stamps onto every <c>viewer_acquire_history</c> row written from this transaction. Callers
+/// that don't set <see cref="Source"/> end up with <see cref="GrantSource.Unknown"/> rows;
+/// grep for <c>acquire_type=0</c> in dev to find unmigrated sites.
+/// </para>
 /// </summary>
 public sealed class InventoryLoadConfig
 {
     internal List<Func<IQueryable<Viewer>, IQueryable<Viewer>>> Includes { get; } = new();
 
+    /// <summary>
+    /// Logical source of every grant queued in this transaction. Defaults to
+    /// <see cref="GrantSource.Unknown"/>.
+    /// </summary>
+    public GrantSource Source { get; set; } = GrantSource.Unknown;
+
     public InventoryLoadConfig WithInclude<TProperty>(
         Expression<Func<Viewer, TProperty>> path)
     {