Fix time entry 500 and inventory edit pencil visibility

- Remove parseInt() from time entry worker select — GUIDs were destroyed
  to NaN → sent as null → FindByIdAsync(null) threw 500
- Ledger pencil: also show for Adjustment rows (no PO) so scan-without-job
  entries get an edit button, not just JobUsage rows
- InventoryController: always write JobUsage type for scan-based logs;
  accept Adjustment in edit endpoints; promote Adjustment→JobUsage when
  a job is assigned via edit

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

src/PowderCoating.Web/Views/Inventory/Ledger.cshtml

@@ -205,7 +205,7 @@
                             </td>
                             <td><small class="text-muted">@t.Notes</small></td>
                             <td>
-                                @if (t.TransactionType == "JobUsage")
+                                @if (t.TransactionType == "JobUsage" || (t.TransactionType == "Adjustment" && t.PurchaseOrderId == null))
                                 {
                                     <button type="button" class="btn btn-outline-secondary btn-sm py-0 px-1"
                                             title="Edit usage record"