Add CRM features: Additional Contacts, Lead Source, Ship-To Address; update Help docs

- New CustomerContact entity + migration (AddCustomerContactsAndCrmFields)
- Customer.LeadSource + ShipToAddress/City/State/ZipCode/Country fields
- Additional Contacts card on Customer Details with AJAX add/edit/delete
- Lead Source dropdown on Create/Edit; Ship-To section on Create/Edit
- Customer Details: side-by-side billing/ship-to when ship-to is set
- Help docs: Customers (contacts, ship-to, lead source, preferred powders, outstanding pickups)
- Help docs: Jobs (clone job, project name), Quotes (project name), Invoices (project name), Inventory (low stock clickable filter)
- HelpKnowledgeBase.cs updated for all features above

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

src/PowderCoating.Application/DTOs/Customer/CustomerContactDtos.cs

@@ -0,0 +1,64 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace PowderCoating.Application.DTOs.Customer;
+
+public class CustomerContactDto
+{
+    public int Id { get; set; }
+    public int CustomerId { get; set; }
+    public string FirstName { get; set; } = string.Empty;
+    public string? LastName { get; set; }
+    public string? Title { get; set; }
+    public string? ContactRole { get; set; }
+    public string? Email { get; set; }
+    public string? Phone { get; set; }
+    public string? MobilePhone { get; set; }
+    public string? Notes { get; set; }
+
+    public string DisplayName => string.IsNullOrWhiteSpace(LastName) ? FirstName : $"{FirstName} {LastName}";
+}
+
+public class CreateCustomerContactDto
+{
+    [Required(ErrorMessage = "First name is required.")]
+    [StringLength(100)]
+    [Display(Name = "First Name")]
+    public string FirstName { get; set; } = string.Empty;
+
+    [StringLength(100)]
+    [Display(Name = "Last Name")]
+    public string? LastName { get; set; }
+
+    [StringLength(100)]
+    [Display(Name = "Job Title")]
+    public string? Title { get; set; }
+
+    [StringLength(50)]
+    [Display(Name = "Role")]
+    public string? ContactRole { get; set; }
+
+    [EmailAddress]
+    [StringLength(200)]
+    [Display(Name = "Email")]
+    public string? Email { get; set; }
+
+    [Phone]
+    [StringLength(20)]
+    [Display(Name = "Phone")]
+    public string? Phone { get; set; }
+
+    [Phone]
+    [StringLength(20)]
+    [Display(Name = "Mobile Phone")]
+    public string? MobilePhone { get; set; }
+
+    [StringLength(500)]
+    [Display(Name = "Notes")]
+    public string? Notes { get; set; }
+}
+
+public class UpdateCustomerContactDto : CreateCustomerContactDto
+{
+    public int Id { get; set; }
+    public int CustomerId { get; set; }
+}

src/PowderCoating.Application/DTOs/Customer/CustomerDtos.cs

@@ -36,6 +36,16 @@ public class CustomerDto
     public bool NotifyBySms { get; set; }
     public DateTime? SmsConsentedAt { get; set; }
     public string? SmsConsentMethod { get; set; }
+
+    // CRM
+    public string? LeadSource { get; set; }
+
+    // Ship-to address
+    public string? ShipToAddress { get; set; }
+    public string? ShipToCity { get; set; }
+    public string? ShipToState { get; set; }
+    public string? ShipToZipCode { get; set; }
+    public string? ShipToCountry { get; set; }
 }
 
 public class CreateCustomerDto : IValidatableObject
@@ -115,6 +125,31 @@ public class CreateCustomerDto : IValidatableObject
     [StringLength(2000)]
     public string? GeneralNotes { get; set; }
 
+    [Display(Name = "How did you find us?")]
+    [StringLength(100)]
+    public string? LeadSource { get; set; }
+
+    // Ship-to / alternate address
+    [Display(Name = "Ship-To Street Address")]
+    [StringLength(500)]
+    public string? ShipToAddress { get; set; }
+
+    [Display(Name = "City")]
+    [StringLength(100)]
+    public string? ShipToCity { get; set; }
+
+    [Display(Name = "State")]
+    [StringLength(50)]
+    public string? ShipToState { get; set; }
+
+    [Display(Name = "Zip Code")]
+    [StringLength(20)]
+    public string? ShipToZipCode { get; set; }
+
+    [Display(Name = "Country")]
+    [StringLength(100)]
+    public string? ShipToCountry { get; set; }
+
     [Display(Name = "Notify by Email")]
     public bool NotifyByEmail { get; set; } = true;
 

src/PowderCoating.Application/Mappings/CustomerProfile.cs

@@ -41,5 +41,12 @@ public class CustomerProfile : Profile
                       opt => opt.MapFrom(src => !string.IsNullOrEmpty(src.ContactFirstName) || !string.IsNullOrEmpty(src.ContactLastName)
                           ? $"{src.ContactFirstName} {src.ContactLastName}".Trim()
                           : string.Empty));
+
+        // CustomerContact
+        CreateMap<CustomerContact, CustomerContactDto>();
+        CreateMap<CreateCustomerContactDto, CustomerContact>();
+        CreateMap<UpdateCustomerContactDto, CustomerContact>()
+            .ForMember(dest => dest.Id, opt => opt.Ignore()); // Id is set by the controller, not mapped
+        CreateMap<CustomerContact, UpdateCustomerContactDto>();
     }
 }