Fix C# nullable reference warnings in SolidWorks service

- Use object? for ref parameters in GetAll3 calls
- Add null-forgiving operator (!) after IsNullOrEmpty checks
- Fixes 10 compiler warnings

Author: eldinmiller

solidworks-service/BluePLM.SolidWorksService/DocumentManagerAPI.cs

@@ -156,8 +156,8 @@ public bool Initialize()
                     return false;
                 }
 
-                // Log key info (masked for security)
-                var keyPrefix = key.Length > 30 ? key.Substring(0, 30) + "..." : key;
+                // Log key info (masked for security) - key is non-null after IsNullOrEmpty check
+                var keyPrefix = key!.Length > 30 ? key.Substring(0, 30) + "..." : key;
                 var keyLength = key.Length;
                 var hasCommas = key.Contains(",");
                 var hasColon = key.Contains(":");
@@ -797,7 +797,7 @@ private Dictionary<string, string> ReadProperties(dynamic doc, string? configura
                                 if (!string.IsNullOrEmpty(value))
                                 {
                                     Console.Error.WriteLine($"[DM] Property '{name}' = '{value}'");
-                                    props[name] = value;
+                                    props[name!] = value;
                                 }
                                 else
                                 {
@@ -849,7 +849,7 @@ private Dictionary<string, string> ReadProperties(dynamic doc, string? configura
                                 if (!string.IsNullOrEmpty(name))
                                 {
                                     Console.Error.WriteLine($"[DM] Property[{i}] '{name}' = '{value}'");
-                                    props[name] = value ?? "";
+                                    props[name!] = value ?? "";
                                 }
                             }
                             catch (Exception indexEx)
@@ -942,7 +942,7 @@ private Dictionary<string, string> ReadProperties(dynamic doc, string? configura
 
                                         if (!string.IsNullOrEmpty(value))
                                         {
-                                            props[name] = value;
+                                            props[name!] = value;
                                             Console.Error.WriteLine($"[DM] Config property '{name}' = '{value}'");
                                         }
                                     }

solidworks-service/BluePLM.SolidWorksService/SolidWorksAPI.cs

@@ -792,7 +792,7 @@ ref warnings
                 else if (!string.IsNullOrEmpty(configuration))
                 {
                     // Export single configuration
-                    configsToExport = new[] { configuration };
+                    configsToExport = new[] { configuration! };
                 }
                 else
                 {
@@ -814,7 +814,7 @@ ref warnings
                         string configOutputPath;
                         if (!string.IsNullOrEmpty(filenamePattern))
                         {
-                            var fileName = FormatExportFilename(filenamePattern, baseName, configName, props, ".step", pdmMetadata);
+                            var fileName = FormatExportFilename(filenamePattern!, baseName, configName, props, ".step", pdmMetadata);
                             configOutputPath = Path.Combine(outputDir, fileName);
                         }
                         else
@@ -1430,7 +1430,7 @@ private Dictionary<string, string> GetConfigProperties(ModelDoc2 doc, string con
                 var fileManager = doc.Extension.CustomPropertyManager[""];
                 if (fileManager != null)
                 {
-                    object names = null, values = null, resolved = null, types = null, linkedProps = null;
+                    object? names = null, values = null, resolved = null, types = null, linkedProps = null;
                     fileManager.GetAll3(ref names, ref types, ref values, ref resolved, ref linkedProps);
 
                     var propNames = names as string[];
@@ -1463,7 +1463,7 @@ private Dictionary<string, string> GetConfigProperties(ModelDoc2 doc, string con
                     var configManager = doc.Extension.CustomPropertyManager[configName];
                     if (configManager != null)
                     {
-                        object names = null, values = null, resolved = null, types = null, linkedProps = null;
+                        object? names = null, values = null, resolved = null, types = null, linkedProps = null;
                         configManager.GetAll3(ref names, ref types, ref values, ref resolved, ref linkedProps);
 
                         var propNames = names as string[];