refactor: migrate Newtonsoft.Json to System.Text.Json and bump Roslyn

- Removed Newtonsoft.Json dependency entirely
- Serialization now uses System.Text.Json with a custom
  LowercaseNamingPolicy (same output format as before)
- Microsoft.CodeAnalysis.CSharp bumped 4.5.0 → 4.12.0
- Microsoft.CodeAnalysis.Analyzers bumped 3.3.3 → 3.11.0

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: TheSmallPixel

tools/CodeAnalysisTool/CodeAnalysisTool.csproj

@@ -5,12 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <!-- Roslyn compiler APIs for code analysis -->
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.5.0" />
-    <!-- Analyzers for Roslyn (optional but often recommended). 
-         Set PrivateAssets to 'all' so they don't flow to consumers of your tool. -->
-    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.3" PrivateAssets="all" />
-    <!-- Newtonsoft.Json to serialize your final D3 graph, if you're using that -->
-    <PackageReference Include="Newtonsoft.Json" Version="13.0.2" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.12.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.11.0" PrivateAssets="all" />
   </ItemGroup>
 </Project>

tools/CodeAnalysisTool/Program.cs

@@ -6,8 +6,8 @@
 using System.Reflection;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Serialization;
+using System.Text.Json;
+using System.Text.Json.Serialization;
 
 namespace CodeAnalysisTool
 {
@@ -129,19 +129,14 @@ static void Main(string[] args)
                 {
                     Directory.CreateDirectory(docsPath);
                     var outputFile = Path.Combine(docsPath, "graph.json");
-                    
-                    // Create settings specifying our custom naming strategy
-                    var settings = new JsonSerializerSettings
+
+                    var options = new JsonSerializerOptions
                     {
-                        // Use a DefaultContractResolver with our LowercaseNamingStrategy
-                        ContractResolver = new DefaultContractResolver
-                        {
-                            NamingStrategy = new LowercaseNamingStrategy()
-                        },
-                        Formatting = Formatting.Indented // for pretty printing
+                        PropertyNamingPolicy = new LowercaseNamingPolicy(),
+                        WriteIndented = true
                     };
-                    
-                    File.WriteAllText(outputFile, JsonConvert.SerializeObject(graph, settings));
+
+                    File.WriteAllText(outputFile, JsonSerializer.Serialize(graph, options));
                     Console.WriteLine($"Generated: {outputFile}");
 
                     // Print some statistics
@@ -243,11 +238,8 @@ private static List<MetadataReference> GetMetadataReferences()
         }
     }
 
-    public class LowercaseNamingStrategy : NamingStrategy
+    public class LowercaseNamingPolicy : JsonNamingPolicy
     {
-        protected override string ResolvePropertyName(string name)
-        {
-            return name.ToLowerInvariant();
-        }
+        public override string ConvertName(string name) => name.ToLowerInvariant();
     }
 }