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/wwwroot/js/item-wizard.js

@@ -82,6 +82,21 @@ document.addEventListener('DOMContentLoaded', () => {
     const ownerForm = hfc?.closest('form');
     if (ownerForm) {
         ownerForm.addEventListener('submit', writeHiddenFields, { capture: true });
+
+        // Save scroll position before the form causes a full-page reload so we can
+        // restore it after the server redirects back to this page. Key is path-specific
+        // so navigating away and back doesn't restore a stale position.
+        const scrollKey = 'wizardScrollY:' + location.pathname;
+        ownerForm.addEventListener('submit', () => {
+            sessionStorage.setItem(scrollKey, String(Math.round(window.scrollY)));
+        }, { capture: true });
+
+        // Restore on load — fire after layout is painted so scrollTo lands correctly.
+        const savedY = sessionStorage.getItem(scrollKey);
+        if (savedY !== null) {
+            sessionStorage.removeItem(scrollKey);
+            requestAnimationFrame(() => window.scrollTo({ top: parseInt(savedY, 10), behavior: 'instant' }));
+        }
     }
 
     // Close any open powder combobox or catalog lookup dropdown when clicking outside it
@@ -2731,8 +2746,9 @@ function buildCardHtml(item, i) {
         const orderBadge = (!c.inventoryItemId && c.powderToOrder)
             ? ` <span class="badge bg-warning text-dark" style="font-size:.65em;vertical-align:middle;" title="Custom powder — must be purchased before coating"><i class="bi bi-cart me-1"></i>ORDER ${parseFloat(c.powderToOrder).toFixed(2)} lbs</span>`
             : '';
+        const coatNotes = c.notes ? `<span class="fst-italic ms-1 opacity-75">— ${escHtml(c.notes)}</span>` : '';
         return `<div style="font-size:.8rem;" class="text-muted mt-1">
-            <i class="bi bi-layers me-1"></i><span class="fw-semibold">${escHtml(c.coatName || 'Coat')}</span>${color ? ` — ${color}${code}` : ''}${orderBadge}
+            <i class="bi bi-layers me-1"></i><span class="fw-semibold">${escHtml(c.coatName || 'Coat')}</span>${color ? ` — ${color}${code}` : ''}${orderBadge}${coatNotes}
         </div>`;
     }).join('');
 
@@ -3414,7 +3430,7 @@ function loadItemsFromTemplate(templateItems) {
             coverageSqFtPerLb:  c.coverageSqFtPerLb || 30,
             transferEfficiency: c.transferEfficiency || 65,
             powderCostPerLb:    c.powderCostPerLb || null,
-            noExtraLayerCharge: false
+            noExtraLayerCharge: !!c.noExtraLayerCharge
         })),
         prepServices: (ti.prepServices || []).map(p => ({
             prepServiceId:   p.prepServiceId,