Fix time entry workers, powder usage logging, inventory edit, and mojibake

- JobTimeEntry: migrate to UserId/UserDisplayName; make ShopWorkerId nullable
  (migration MigrateTimeEntriesToUserId)
- Log Time modal: populate worker dropdown from Identity users instead of
  ShopWorkers; fix ShopMobile view same issue
- Inventory Ledger: scan-based JobUsage transactions now appear in
  Powder Usage By Job tab (synthesized from InventoryTransaction)
- Inventory Ledger: add Edit button for JobUsage transactions; new
  GetUsageForEdit + EditUsageTransaction endpoints; inventory-ledger.js
- InventoryTransactionRepository: include Job.Customer for ledger queries
- InventoryAiLookupService: handle JSON-LD @graph wrapper (Columbia
  Coatings / WooCommerce+Yoast); add HTML price snippet fallback
- Fix mojibake in 9 views: â†' → →, âœ" → ✓, âš  → ⚠

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

src/PowderCoating.Web/Views/PlatformNotifications/Index.cshtml

@@ -202,7 +202,7 @@
                             </div>
                         </div>
                         <div class="mobile-card-footer">
-                            <span class="btn btn-sm btn-outline-secondary">View →</span>
+                            <span class="btn btn-sm btn-outline-secondary">View →</span>
                         </div>
                     </a>
                 }