Phase 1: Project scaffolding and infrastructure

- Scaffold Budget.Api (ASP.NET Core Web API, net10.0) with EF Core + Npgsql
- Scaffold Budget.Client (Vite + React + TypeScript) with /api proxy to localhost:5000
- Define all entity models: Budget, Income, Outgo, KnownUser, BudgetShare
- Configure AppDbContext with EF mappings and cascade deletes
- Add InitialCreate migration
- Configure SPA static file serving + fallback in Program.cs
- Add Dockerfile (multi-stage: node + dotnet sdk + aspnet runtime)
- Add .env.example with all required environment variables

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Budget.Api/Budget.Api.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="10.0.7" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="10.0.7">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="10.0.1" />
+  </ItemGroup>
+
+</Project>