.csproj File Conventions

This rule applies to files matching the patterns above.

# .csproj File Conventions

## Rule
All projects MUST use SDK-style .csproj format. Shared settings go in Directory.Build.props. Package references must be alphabetically ordered. Use property groups for NuGet package metadata.

## Good Examples
```xml
<!-- Directory.Build.props — shared across all projects -->
<Project>
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
    <NuGetAudit>true</NuGetAudit>
    <NuGetAuditLevel>moderate</NuGetAuditLevel>
  </PropertyGroup>
</Project>

<!-- Application .csproj — clean and minimal -->
<Project Sdk="Microsoft.NET.Sdk.Web">
  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore" />
    <PackageReference Include="Serilog.AspNetCore" />
    <PackageReference Include="Swashbuckle.AspNetCore" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Shared\Shared.csproj" />
  </ItemGroup>
</Project>

<!-- Library .csproj — with NuGet metadata -->
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <PackageId>MyOrg.SharedLib</PackageId>
    <Version>1.2.0</Version>
    <Description>Shared utilities for MyOrg services</Description>
    <Authors>MyOrg</Authors>
    <PackageLicenseExpression>MIT</PackageLicenseExpression>
    <PackageReadmeFile>README.md</PackageReadmeFile>
    <GenerateDocumentationFile>true</GenerateDocumentationFile>
  </PropertyGroup>
</Project>
```

## Bad Examples
```xml
<!-- BAD: Duplicated settings in every project -->
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <Nullable>enable</Nullable>
    <!-- Repeated in every .csproj — use Directory.Build.props -->
  </PropertyGroup>
</Project>

<!-- BAD: Old-style .csproj with GUIDs -->
<Project ToolsVersion="15.0">
  <Import Project="$(MSBuildExtensionsPath)..." />
  <PropertyGroup>
    <ProjectGuid>{GUID-HERE}</ProjectGuid>
    <!-- Migrate to SDK-style -->
  </PropertyGroup>
</Project>
```

## Enforcement
- `dotnet format` for consistent formatting
- TreatWarningsAsErrors in Directory.Build.props
- CI validates NuGet audit passes with no vulnerabilities