Add invoice SMS notifications and customer intake kiosk

Invoice SMS:
- Send Invoice modal now prompts Email/SMS/Both based on customer contact data
- New /invoice/{token} customer-facing view page with full line items and pay button
- PublicViewToken (permanent) added to Invoice; separate from expiring PaymentLinkToken
- InvoiceSent SMS default template added; customizable via Notification Templates settings
- {{viewUrl}} placeholder documented in template editor

Customer Intake Kiosk:
- Tablet kiosk flow: Contact → Job → Terms/Signature → Confirmation
- Remote link mode for off-site customers (lighter form, no signature)
- KioskHub (AllowAnonymous SignalR) for staff-to-tablet push without login
- Staff activates tablet via cookie; sends remote link manually
- Submitted sessions create Customer + Job automatically; fires in-app notification

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

src/PowderCoating.Infrastructure/Data/SeedData.cs

@@ -967,6 +967,17 @@ New accounts walk through an 18-step setup wizard to configure company informati
                 CreatedAt = DateTime.UtcNow
             },
             new NotificationTemplate
+            {
+                NotificationType = NotificationType.InvoiceSent,
+                Channel = NotificationChannel.Sms,
+                DisplayName = "Invoice Sent (SMS)",
+                Subject = null,
+                Body = "{{companyName}}: Invoice {{invoiceNumber}} for {{invoiceTotal}} is ready. View your invoice: {{viewUrl}} Reply STOP to opt out.",
+                IsActive = true,
+                CompanyId = companyId,
+                CreatedAt = DateTime.UtcNow
+            },
+            new NotificationTemplate
             {
                 NotificationType = NotificationType.PaymentReceived,
                 Channel = NotificationChannel.Email,