fix: preserve original file type on upload — never convert PNG to JPG

Problem: cropper always called out.toBlob(..., 'image/jpeg') regardless
of the original file type, silently converting PNGs to JPGs.

Fix:
- openCropper() now stores file.type and file.name on the cropper object
- applyCrop() uses the stored mime type for toBlob() and the filename
- Quality param only passed for lossy formats (jpeg/webp), not for PNG/GIF
- uploadImage() accept list expanded: svg, ico allowed
- Server-side: .svg and .ico added to allowed extensions

Result: PNG stays PNG, WebP stays WebP, ICO stays ICO.

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

DrSousan.Api/Program.cs

@@ -589,7 +589,7 @@ app.MapPost("/api/upload", async (HttpRequest request, IWebHostEnvironment env)
     if (!request.HasFormContentType || !request.Form.Files.Any())
         return Results.BadRequest("No file provided.");
     var file    = request.Form.Files[0];
-    var allowed = new[] { ".jpg", ".jpeg", ".png", ".webp", ".gif" };
+    var allowed = new[] { ".jpg", ".jpeg", ".png", ".webp", ".gif", ".svg", ".ico" };
     var ext     = Path.GetExtension(file.FileName).ToLowerInvariant();
     if (!allowed.Contains(ext)) return Results.BadRequest("File type not allowed.");
     var uploadsDir = Path.Combine(env.WebRootPath, "uploads");