Fix NoExtraLayerCharge persistence, appointment reminders, coat notes display, scroll restoration, and invoice Send dead-button

- Appointment reminders: add AppointmentReminderBackgroundService (60s poll), ReminderSentAt
  dedup stamp, NotifyAppointmentReminderAsync sends both customer email and creator staff email;
  AppointmentReminderStaff notification type + default template added; DateTime.Now used instead
  of UtcNow to match locally-stored ScheduledStartTime; ToLocalTime() double-conversion removed

- NoExtraLayerCharge not persisted: flag existed on CreateQuoteItemCoatDto and was used by
  pricing engine but never written to JobItemCoat/QuoteItemCoat entities — every edit reset it
  to false and re-applied the extra layer charge; added column to both entities (migration
  AddNoExtraLayerChargeToCoats), both read DTOs, all 3 JobItemAssemblyService overloads,
  JobItemCoatSeed inner class, and existingItemsData JSON in all 5 wizard views; fixed JS
  template path that hard-coded noExtraLayerCharge: false

- Coat notes not visible: notes were rendered in desktop job details but missing from the wizard
  item card summary and the mobile card view; both fixed

- Scroll position lost on item save: sessionStorage save/restore added to item-wizard.js owner
  form submit handler; path-keyed so cross-page navigation does not restore stale position;
  requestAnimationFrame used for reliable mobile scroll restoration

- Invoice Send dead button: #sendChannelModal was gated inside @if (isDraft) but the button
  targeting it fires for Sent/Overdue invoices too when customer has both email and SMS; modal
  moved outside the Draft guard

- InitialCreate migration added for fresh database installs; Baseline migration guarded with
  IF OBJECT_ID check so it no-ops on fresh DBs; Razor scoping bug fixed in Customers/Index.cshtml

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

src/PowderCoating.Web/Views/Jobs/Details.cshtml

@@ -653,7 +653,10 @@
                                                 <span class="mobile-card-value">
                                                     @foreach (var coat in item.Coats.OrderBy(c => c.Sequence))
                                                     {
-                                                        <small class="d-block">@coat.CoatName@if (!string.IsNullOrEmpty(coat.ColorName)) { <text> &ndash; @coat.ColorName</text> }</small>
+                                                        <small class="d-block">
+                                                            @coat.CoatName@if (!string.IsNullOrEmpty(coat.ColorName)) { <text> &ndash; @coat.ColorName</text> }
+                                                            @if (!string.IsNullOrEmpty(coat.Notes)) { <text><br /><span class="fst-italic text-muted ms-2">@coat.Notes</span></text> }
+                                                        </small>
                                                     }
                                                 </span>
                                             </div>