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>

.env.example

@@ -0,0 +1,15 @@
+# Database
+POSTGRES_HOST=db
+POSTGRES_PORT=5432
+POSTGRES_DB=budget
+POSTGRES_USER=budget
+POSTGRES_PASSWORD=changeme
+
+# Auth
+AUTH__AUTHORITY=https://auth.stwaddle.com
+AUTH__AUDIENCE=budget-api
+
+# Client (baked into Vite build)
+VITE_AUTH_AUTHORITY=https://auth.stwaddle.com
+VITE_AUTH_CLIENT_ID=budget-client
+VITE_AUTH_REDIRECT_URI=https://budget.stwaddle.com/callback