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/ApplicationDbContext.cs

@@ -367,6 +367,10 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
     /// <summary>Prep-service definitions within a job template item.</summary>
     public DbSet<JobTemplateItemPrepService> JobTemplateItemPrepServices { get; set; }
 
+    // Customer Intake Kiosk
+    /// <summary>Customer self-service intake sessions (walk-in tablet or remote email link); tenant-filtered with soft delete.</summary>
+    public DbSet<KioskSession> KioskSessions { get; set; }
+
     /// <summary>
     /// Platform-wide audit log capturing who changed what and when, across all tenants.
     /// No global query filter — SuperAdmin controllers query this directly.
@@ -746,6 +750,24 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
         modelBuilder.Entity<InAppNotification>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
 
+        // Customer intake kiosk sessions — tenant-filtered + soft delete.
+        // Anonymous intake routes must use ignoreQueryFilters:true when loading by SessionToken.
+        modelBuilder.Entity<KioskSession>().HasQueryFilter(e =>
+            !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
+        modelBuilder.Entity<KioskSession>()
+            .HasIndex(e => e.SessionToken)
+            .IsUnique();
+        modelBuilder.Entity<KioskSession>()
+            .HasOne(k => k.LinkedCustomer)
+            .WithMany()
+            .HasForeignKey(k => k.LinkedCustomerId)
+            .OnDelete(DeleteBehavior.SetNull);
+        modelBuilder.Entity<KioskSession>()
+            .HasOne(k => k.LinkedJob)
+            .WithMany()
+            .HasForeignKey(k => k.LinkedJobId)
+            .OnDelete(DeleteBehavior.SetNull);
+
         // Account self-referencing hierarchy
         modelBuilder.Entity<Account>()
             .HasOne(a => a.ParentAccount)