feat(ci): Add GitHub Actions workflows for test automation and status badges

Add comprehensive test automation setup with GitHub Actions:
- Create test.yml for running tests on main/develop branches
- Add pr-test.yml for PR validation with test results comments
- Add update-badges.yml for dynamic test status badge updates
- Configure code coverage reporting with Codecov integration

Documentation:
- Add BADGE_SETUP.md with instructions for configuring test status badges
- Add WORKFLOWS_GUIDE.md explaining CI/CD workflow setup
- Update README.md with build and test status badges

Test Framework:
- Configure test project to use .NET 9.0
- Set up test coverage reporting with coverlet
- Add integration tests with WireMock for API mocking
- Add unit tests for configuration and HTTP client components
- Document testing strategy in TestingStrategy.md

Build:
- Add Dockerfile.test for containerized testing
- Update .gitignore for test artifacts
- Configure test dependencies in VRCAuthProxy.Tests.csproj

This change enables automated testing on PRs and branches, with visual status indicators and detailed test results in PR comments.

Tests/VRCAuthProxy.Tests.csproj

@@ -0,0 +1,32 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
+    <PackageReference Include="xunit" Version="2.6.6" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.6">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="6.0.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Moq" Version="4.20.70" />
+    <PackageReference Include="FluentAssertions" Version="6.12.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.0" />
+    <PackageReference Include="WireMock.Net" Version="1.5.44" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\VRCAuthProxy\VRCAuthProxy.csproj" />
+  </ItemGroup>
+
+</Project>