Commit remaining unstaged changes from this session

- Platform settings service: IPlatformSettingsService, PlatformSettingKeys,
  PlatformSettingsService, SubscriptionService, AppConstants,
  SubscriptionExpiryBackgroundService, SubscriptionMiddleware
- JobTimeEntry entity, DTOs, AutoMapper profile (ShopWorker → UserId migration)
- InventoryDtos: SourceTransactionId on PowderUsageLogDto
- InventoryTransactionRepository: include Job.Customer in ledger query
- InventoryAiLookupService: @graph unwrap + HTML price fallback
- ApplicationDbContextModelSnapshot: reflect migration changes
- launchSettings.json, publish profile

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

src/PowderCoating.Application/DTOs/Inventory/InventoryDtos.cs

@@ -258,6 +258,8 @@ public class PowderUsageLogDto
     public decimal VarianceLbs { get; set; }
     public DateTime RecordedAt { get; set; }
     public string? Notes { get; set; }
+    /// <summary>Set only for rows synthesized from a scan-based InventoryTransaction (no PowderUsageLog record).</summary>
+    public int? SourceTransactionId { get; set; }
 }
 
 public class InventoryLedgerViewModel