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/Repositories/UnitOfWork.cs

@@ -121,6 +121,9 @@ public class UnitOfWork : IUnitOfWork
     private IRepository<GiftCertificate>? _giftCertificates;
     private IRepository<GiftCertificateRedemption>? _giftCertificateRedemptions;
 
+    // Customer Intake Kiosk
+    private IRepository<KioskSession>? _kioskSessions;
+
     // Purchase Orders
     private IPurchaseOrderRepository? _purchaseOrders;
     private IRepository<PurchaseOrderItem>? _purchaseOrderItems;
@@ -460,6 +463,10 @@ public class UnitOfWork : IUnitOfWork
     public IRepository<GiftCertificateRedemption> GiftCertificateRedemptions =>
         _giftCertificateRedemptions ??= new Repository<GiftCertificateRedemption>(_context);
 
+    /// <summary>Repository for <see cref="KioskSession"/> customer self-service intake sessions; tenant-filtered with soft delete.</summary>
+    public IRepository<KioskSession> KioskSessions =>
+        _kioskSessions ??= new Repository<KioskSession>(_context);
+
     // Job Templates
     /// <summary>Repository for <see cref="JobTemplate"/> reusable job blueprints; tenant-filtered with soft delete.</summary>
     public IJobTemplateRepository JobTemplates =>