feat: add GET /drawings/{name}/dxf endpoint to export PEP drawings as DXF

PepApi.Core/Controllers/DrawingsController.cs

@@ -2,6 +2,7 @@ using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
 using PepApi.Core.Models;
 using PepLib.Data;
+using PepLib.IO;
 
 namespace PepApi.Core.Controllers;
 
@@ -147,6 +148,38 @@ public class DrawingsController : ControllerBase
         });
     }
 
+    /// <summary>
+    /// Export a drawing as a DXF file.
+    /// </summary>
+    [HttpGet("{name}/dxf")]
+    public async Task<IActionResult> GetDrawingDxf(string name)
+    {
+        var drawing = await _db.Drawings
+            .Where(d => d.Name.ToUpper() == name.ToUpper())
+            .FirstOrDefaultAsync();
+
+        if (drawing == null)
+            return NotFound(new { message = "Drawing not found in database" });
+
+        var filePath = drawing.Path + drawing.File;
+
+        if (!System.IO.File.Exists(filePath))
+            return NotFound(new { message = "Drawing file not found on disk" });
+
+        PepLib.Models.Drawing pep;
+        try
+        {
+            pep = PepLib.Models.Drawing.Load(filePath);
+        }
+        catch (Exception ex)
+        {
+            return StatusCode(500, new { message = $"Failed to load drawing: {ex.Message}" });
+        }
+
+        var stream = DrawingDxfExporter.Export(pep);
+        return File(stream, "application/dxf", $"{name}.dxf");
+    }
+
     private static DrawingDetails ConvertToDetails(Drawing drawing)
     {
         return new DrawingDetails