Upgrade to .NET 10 and finalize foundation scaffold

AGENTS.md

@@ -7,7 +7,7 @@ This repo is a tiny, purpose-built web app for a closed Discord group to:
 4) reveal totals sorted by score
 
 Tech constraints:
-- .NET 8
+- .NET 10
 - ASP.NET Core Minimal API
 - Static HTML/CSS/JS (no Razor Pages, no Blazor, no HTMX)
 - SQLite via EF Core
@@ -76,3 +76,4 @@ Do not introduce MVC controllers, Razor Pages, Blazor, or SPA frameworks.
 - Implement API first, UI second
 - Keep changes small and testable
 - Prefer clarity over abstraction
+- After every iteration, do a git commit with a brief summary of the changes as a commit message.