Add project files.

Dockerfile

@@ -0,0 +1,21 @@
+FROM mcr.microsoft.com/dotnet/aspnet:10.0-preview AS base
+WORKDIR /app
+EXPOSE 8080
+
+FROM mcr.microsoft.com/dotnet/sdk:10.0-preview AS build
+WORKDIR /src
+COPY BudgetApp/BudgetApp.csproj BudgetApp/
+RUN dotnet restore BudgetApp/BudgetApp.csproj
+COPY BudgetApp/ BudgetApp/
+WORKDIR /src/BudgetApp
+RUN dotnet publish -c Release -o /app/publish
+
+FROM base AS final
+WORKDIR /app
+COPY --from=build /app/publish .
+
+# Ensure the SQLite data directory exists and is writable
+RUN mkdir -p /app/data
+ENV ConnectionStrings__DefaultConnection="Data Source=/app/data/budgetapp.db"
+
+ENTRYPOINT ["dotnet", "BudgetApp.dll"]