Show every game on the home page instead of redirecting to Balote #7

With more games, / should let a person pick one in one tap rather than dropping them into Balote.

Done looks like:

• [ ] / (root index.html) is a plain page on white listing every game in GAMES with its title and one-line description from the README table, each a link to <id>/; no meta refresh.
• [ ] The list is generated from one source of truth (shell.js GAMES gains a blurb field, and the home page renders from it) so a new game appears without editing the home page.
• [ ] Works without JavaScript for at least the links (a static <noscript>/fallback list is acceptable if kept in sync by a test).
• [ ] serve.test.mjs: / answers 200 and links every game id in GAMES; the old url=balote/ assertion is replaced, and bun test passes.

Files: index.html, shell.js, serve.test.mjs, README.md. Risk: conflicts with in-flight new-game issues over GAMES; land after them. Fits: a builder.