feat: initial project setup

- Add .NET 8 backend with Clean Architecture
- Add React + Vite + TypeScript frontend
- Implement authentication with JWT
- Implement Azure Blob Storage client
- Implement OCR integration
- Implement supplier matching service
- Implement voucher generation
- Implement Fortnox provider
- Add unit and integration tests
- Add Docker Compose configuration

backend/Directory.Build.props

@@ -0,0 +1,18 @@
+<Project>
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <CodeAnalysisRuleSet>$(MSBuildThisFileDirectory)CodeAnalysis.ruleset</CodeAnalysisRuleSet>
+    <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
+    <LangVersion>12.0</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.556">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+</Project>