Apply template consistency updates from TemplateDotNetTool (Polyfill, LangVersion, ThrowIfNull, AgentFiles)

AGENTS.md

@@ -70,6 +70,7 @@ ReqStream/
   - `Assert.HasCount(collection, expectedCount)` instead of `Assert.AreEqual(count, collection.Count)`
   - `Assert.IsEmpty(collection)` instead of `Assert.AreEqual(0, collection.Count)`
   - `Assert.DoesNotContain(item, collection)` for negative checks
+  - `Assert.StartsWith("prefix", value)` instead of `Assert.IsTrue(value.StartsWith("prefix"))`
 - **Console Testing**: Save and restore `Console.Out` in tests that modify console output:
 
   ```csharp

src/DemaConsulting.ReqStream/Context.cs

@@ -134,6 +134,9 @@ private Context()
     /// <exception cref="ArgumentException">Thrown when arguments are invalid.</exception>
     public static Context Create(string[] args)
     {
+        // Validate input
+        ArgumentNullException.ThrowIfNull(args);
+
         // Initialize flag variables
         var version = false;
         var help = false;

src/DemaConsulting.ReqStream/DemaConsulting.ReqStream.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
-    <LangVersion>12</LangVersion>
+    <LangVersion>latest</LangVersion>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 
@@ -50,13 +50,25 @@
     <PackageReference Include="DemaConsulting.TestResults" Version="1.5.0" />
     <PackageReference Include="Microsoft.Extensions.FileSystemGlobbing" Version="10.0.3" />
     <PackageReference Include="YamlDotNet" Version="16.3.0" />
+    <!-- PrivateAssets="All" prevents these build-time-only packages from becoming transitive dependencies -->
     <PackageReference Include="Microsoft.Sbom.Targets" Version="4.1.5" PrivateAssets="All" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="10.0.103" PrivateAssets="All" />
+    <!--
+      Analyzer and source-only packages require both PrivateAssets and IncludeAssets:
+        PrivateAssets="all"   - prevents these build-time assets from flowing to consumers
+        IncludeAssets         - explicitly enables contentfiles (source injection) and
+                                analyzers/buildtransitive (Roslyn analyzers at compile time)
+    -->
     <PackageReference Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="10.0.103">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="SonarAnalyzer.CSharp" Version="10.19.0.132793">
+    <PackageReference Include="SonarAnalyzer.CSharp" Version="10.20.0.135146">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <!-- Polyfill is a source-only package; contentfiles delivers the polyfill source into this project -->
+    <PackageReference Include="Polyfill" Version="9.12.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>

src/DemaConsulting.ReqStream/Validation.cs

@@ -35,6 +35,9 @@ public static class Validation
     /// <param name="context">The context containing command line arguments and program state.</param>
     public static void Run(Context context)
     {
+        // Validate input
+        ArgumentNullException.ThrowIfNull(context);
+
         // Print validation header
         PrintValidationHeader(context);
 

test/DemaConsulting.ReqStream.Tests/DemaConsulting.ReqStream.Tests.csproj

@@ -24,7 +24,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
     <PackageReference Include="MSTest.TestAdapter" Version="4.1.0" />
     <PackageReference Include="MSTest.TestFramework" Version="4.1.0" />
   </ItemGroup>
@@ -35,14 +35,16 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="SonarAnalyzer.CSharp" Version="10.19.0.132793">
+    <PackageReference Include="SonarAnalyzer.CSharp" Version="10.20.0.135146">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
   </ItemGroup>
 
+  <!-- Implicit Usings -->
   <ItemGroup>
     <Using Include="Microsoft.VisualStudio.TestTools.UnitTesting" />
+    <Using Include="Polyfills" />
   </ItemGroup>
 
   <!-- Project References -->