Add Custom Formula Item Templates with AI generation and wizard integration

Introduces per-company reusable NCalc2 pricing formula templates for complex
fabricated items (roof curbs, enclosures, welded frames). Templates support
two output modes — FixedRate (formula yields a dollar amount) and SurfaceAreaSqFt
(formula yields sq ft fed into the standard coating engine). Includes:

- CustomItemTemplate entity, migration (AddCustomItemTemplates), IUnitOfWork repo
- IsCustomFormulaItem / CustomItemTemplateId / FormulaFieldValuesJson flags on
  QuoteItem, JobItem, CreateQuoteItemDto; mapped in all 3 JobItemAssemblyService
  overloads and all existingItemsData JSON projections + pageMeta blocks
- ICustomFormulaAiService / CustomFormulaAiService: Claude-powered formula
  generator (natural language + optional diagram image) and NCalc2 evaluator
- CompanySettings CRUD endpoints: GetCustomItemTemplates, Create/Update/Delete,
  UploadTemplateDiagram, TemplateDiagram (blob serve), EvaluateFormula, GenerateFormulaFromAi
- Company Settings "Custom Formulas" tab + cfModal + company-settings-custom-formulas.js
- item-wizard.js: formula item type card, renderFormulaFields, wzFormulaRecalc
  (live evaluate via POST), collectStep2 formula branch, buildCardHtml / emitHiddenFields
- Formula badge in Quotes/Details and Jobs/Details; AI badge gap fixed in Jobs/Details
- Help article (CustomFormulaTemplates.cshtml), Help Index card, HelpController action,
  HelpKnowledgeBase entry; 225/225 unit tests passing

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

src/PowderCoating.Application/DTOs/Company/CustomItemTemplateDtos.cs

@@ -0,0 +1,174 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace PowderCoating.Application.DTOs.Company;
+
+// ============================================================================
+// LIST DTO - For Company Settings tab table
+// ============================================================================
+public class CustomItemTemplateListDto
+{
+    public int Id { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    public string OutputMode { get; set; } = "FixedRate";
+    public int FieldCount { get; set; }
+    public decimal? DefaultRate { get; set; }
+    public string? RateLabel { get; set; }
+    public bool IsActive { get; set; }
+    public int DisplayOrder { get; set; }
+    public string? DiagramImagePath { get; set; }
+}
+
+// ============================================================================
+// FULL DTO - For Edit modal and formula evaluation
+// ============================================================================
+public class CustomItemTemplateDto
+{
+    public int Id { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    public string OutputMode { get; set; } = "FixedRate";
+    public string FieldsJson { get; set; } = "[]";
+    public string Formula { get; set; } = string.Empty;
+    public decimal? DefaultRate { get; set; }
+    public string? RateLabel { get; set; }
+    public string? Notes { get; set; }
+    public int DisplayOrder { get; set; }
+    public bool IsActive { get; set; }
+    public string? DiagramImagePath { get; set; }
+}
+
+// ============================================================================
+// CREATE DTO
+// ============================================================================
+public class CreateCustomItemTemplateDto
+{
+    [Required]
+    [StringLength(100)]
+    public string Name { get; set; } = string.Empty;
+
+    [StringLength(500)]
+    public string? Description { get; set; }
+
+    /// <summary>"FixedRate" or "SurfaceAreaSqFt"</summary>
+    [Required]
+    public string OutputMode { get; set; } = "FixedRate";
+
+    /// <summary>JSON array of field definitions: [{name, label, unit, defaultValue}]</summary>
+    [Required]
+    public string FieldsJson { get; set; } = "[]";
+
+    [Required]
+    public string Formula { get; set; } = string.Empty;
+
+    public decimal? DefaultRate { get; set; }
+
+    [StringLength(50)]
+    public string? RateLabel { get; set; }
+
+    [StringLength(1000)]
+    public string? Notes { get; set; }
+
+    public int DisplayOrder { get; set; }
+    public bool IsActive { get; set; } = true;
+}
+
+// ============================================================================
+// UPDATE DTO
+// ============================================================================
+public class UpdateCustomItemTemplateDto
+{
+    public int Id { get; set; }
+
+    [Required]
+    [StringLength(100)]
+    public string Name { get; set; } = string.Empty;
+
+    [StringLength(500)]
+    public string? Description { get; set; }
+
+    [Required]
+    public string OutputMode { get; set; } = "FixedRate";
+
+    [Required]
+    public string FieldsJson { get; set; } = "[]";
+
+    [Required]
+    public string Formula { get; set; } = string.Empty;
+
+    public decimal? DefaultRate { get; set; }
+
+    [StringLength(50)]
+    public string? RateLabel { get; set; }
+
+    [StringLength(1000)]
+    public string? Notes { get; set; }
+
+    public int DisplayOrder { get; set; }
+    public bool IsActive { get; set; } = true;
+
+    /// <summary>Existing diagram path — kept if no new file is uploaded.</summary>
+    public string? DiagramImagePath { get; set; }
+}
+
+// ============================================================================
+// WIZARD PICKER DTO - Lean DTO for populating the quote wizard template list
+// ============================================================================
+public class CustomItemTemplatePickerDto
+{
+    public int Id { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    public string OutputMode { get; set; } = "FixedRate";
+    public string FieldsJson { get; set; } = "[]";
+    public string Formula { get; set; } = string.Empty;
+    public decimal? DefaultRate { get; set; }
+    public string? RateLabel { get; set; }
+    public string? DiagramImagePath { get; set; }
+}
+
+// ============================================================================
+// AI GENERATION DTOs
+// ============================================================================
+public class GenerateFormulaFromAiRequest
+{
+    [Required]
+    public string Description { get; set; } = string.Empty;
+}
+
+public class GenerateFormulaFromAiResponse
+{
+    public bool Success { get; set; }
+    public string? Error { get; set; }
+    public string? Name { get; set; }
+    public string? OutputMode { get; set; }
+    public string? FieldsJson { get; set; }
+    public string? Formula { get; set; }
+    public decimal? DefaultRate { get; set; }
+    public string? RateLabel { get; set; }
+    public string? Reasoning { get; set; }
+
+    /// <summary>Result of running the formula with any sample values found in the description.</summary>
+    public decimal? VerificationResult { get; set; }
+    public string? VerificationInputs { get; set; }
+}
+
+// ============================================================================
+// FORMULA EVALUATION DTOs
+// ============================================================================
+public class EvaluateFormulaRequest
+{
+    [Required]
+    public string Formula { get; set; } = string.Empty;
+
+    /// <summary>JSON object of variable name → value pairs, e.g. {"box_l": 43, "rate": 0.05}</summary>
+    [Required]
+    public string VariablesJson { get; set; } = "{}";
+}
+
+public class EvaluateFormulaResponse
+{
+    public bool Success { get; set; }
+    public decimal? Result { get; set; }
+    public string? Error { get; set; }
+}

src/PowderCoating.Application/DTOs/Job/JobDtos.cs

@@ -325,7 +325,11 @@ public class JobItemDto
     public bool IsGenericItem { get; set; }
     public bool IsLaborItem { get; set; }
     public bool IsSalesItem { get; set; }
+    public bool IsAiItem { get; set; }
     public string? Sku { get; set; }
+    public bool IsCustomFormulaItem { get; set; }
+    public int? CustomItemTemplateId { get; set; }
+    public string? FormulaFieldValuesJson { get; set; }
     public List<JobItemCoatDto> Coats { get; set; } = new();
     public List<JobItemPrepServiceDto> PrepServices { get; set; } = new();
 }

src/PowderCoating.Application/DTOs/Quote/QuoteDtos.cs

@@ -475,6 +475,11 @@ public class QuoteItemDto
 
     public bool IsAiItem { get; set; }
 
+    // Custom formula item
+    public bool IsCustomFormulaItem { get; set; }
+    public int? CustomItemTemplateId { get; set; }
+    public string? FormulaFieldValuesJson { get; set; }
+
     // Cost breakdown snapshot
     public decimal ItemMaterialCost { get; set; }
     public decimal ItemLaborCost { get; set; }
@@ -559,6 +564,11 @@ public class CreateQuoteItemDto
 
     // ID of the AiItemPrediction record captured at analysis time (null for non-AI items)
     public int? AiPredictionId { get; set; }
+
+    // Custom formula item routing — see IsCustomFormulaItem in PricingCalculationService
+    public bool IsCustomFormulaItem { get; set; }
+    public int? CustomItemTemplateId { get; set; }
+    public string? FormulaFieldValuesJson { get; set; }
 }
 
 // ============================================================================