feat: Add material dimensions with typed properties

Implement TPH inheritance for material dimensions:
- MaterialShape enum with display names and parsing
- MaterialType enum (Steel, Aluminum, Stainless, etc.)
- MaterialDimensions base class with derived types per shape
- Auto-generate size strings from typed dimensions
- SortOrder field for numeric dimension sorting

Each shape has specific dimension properties:
- RoundBar: Diameter
- RoundTube: OuterDiameter, Wall
- FlatBar: Width, Thickness
- SquareBar/Tube: Size, Wall
- RectangularTube: Width, Height, Wall
- Angle: Leg1, Leg2, Thickness
- Channel: Height, Flange, Web
- IBeam: Height, WeightPerFoot
- Pipe: NominalSize, Wall, Schedule

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CutList.Web/Migrations/20260205025716_UpdateExistingSortOrders.cs

@@ -0,0 +1,41 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace CutList.Web.Migrations
+{
+    /// <inheritdoc />
+    public partial class UpdateExistingSortOrders : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Update SortOrder for existing materials based on their primary dimension
+            migrationBuilder.Sql(@"
+                UPDATE m
+                SET m.SortOrder = CAST(
+                    CASE d.DimensionType
+                        WHEN 'RoundBar' THEN d.Diameter * 1000
+                        WHEN 'RoundTube' THEN d.OuterDiameter * 1000
+                        WHEN 'FlatBar' THEN d.Width * 1000
+                        WHEN 'SquareBar' THEN d.Size * 1000
+                        WHEN 'SquareTube' THEN d.Size * 1000
+                        WHEN 'RectangularTube' THEN d.Width * 1000
+                        WHEN 'Angle' THEN d.Leg1 * 1000
+                        WHEN 'Channel' THEN d.Height * 1000
+                        WHEN 'IBeam' THEN d.Height * 1000
+                        WHEN 'Pipe' THEN d.NominalSize * 1000
+                        ELSE 0
+                    END AS INT)
+                FROM Materials m
+                INNER JOIN MaterialDimensions d ON d.MaterialId = m.Id
+            ");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+
+        }
+    }
+}