Add analyzer and frontend lint guardrails

README.md

@@ -13,6 +13,13 @@ Pick'n'Play is a .NET 10 ASP.NET Core Minimal API app with a static HTML/CSS/JS
 4. Open:
    `http://localhost:5000` (or the URL shown by `dotnet run`)
 
+## Frontend Tooling
+
+- Install tooling: `npm install`
+- Lint JS: `npm run lint`
+- Check formatting: `npm run format:check`
+- Apply formatting: `npm run format`
+
 ## Core Behavior
 
 - Authentication: username/password with HttpOnly `player` cookie.
@@ -44,5 +51,6 @@ Pick'n'Play is a .NET 10 ASP.NET Core Minimal API app with a static HTML/CSS/JS
 GitHub Actions workflow: `.github/workflows/ci.yml`
 
 - Restores dependencies
+- Runs frontend lint and format checks
 - Builds with warnings treated as errors
 - Runs `GameList.Tests`