feat: Add full REST API with controllers, DTOs, and service layer

Add controllers for suppliers, stock items, jobs, cutting tools, and
packing. Refactor MaterialsController to use MaterialService with
dimension-aware CRUD, search, and bulk operations. Extract DTOs into
dedicated files.

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

CutList.Web/DTOs/PackingDtos.cs

@@ -0,0 +1,45 @@
+namespace CutList.Web.DTOs;
+
+public class StandalonePackRequestDto
+{
+    public List<PartInputDto> Parts { get; set; } = new();
+    public List<StockBinInputDto> StockBins { get; set; } = new();
+    public decimal Kerf { get; set; } = 0.125m;
+    public string Strategy { get; set; } = "advanced";
+}
+
+public class PartInputDto
+{
+    public string Name { get; set; } = string.Empty;
+    public string Length { get; set; } = string.Empty;
+    public int Quantity { get; set; } = 1;
+}
+
+public class StockBinInputDto
+{
+    public string Length { get; set; } = string.Empty;
+    public int Quantity { get; set; } = -1;
+    public int Priority { get; set; } = 25;
+}
+
+public class ParseLengthRequestDto
+{
+    public string Input { get; set; } = string.Empty;
+}
+
+public class ParseLengthResponseDto
+{
+    public double Inches { get; set; }
+    public string Formatted { get; set; } = string.Empty;
+}
+
+public class FormatLengthRequestDto
+{
+    public double Inches { get; set; }
+}
+
+public class FormatLengthResponseDto
+{
+    public string Formatted { get; set; } = string.Empty;
+    public double Inches { get; set; }
+}