The scripts under showcase/scripts/ run via tsx at runtime and had no
tsconfig.json, which left LSP falling back to no-config defaults and
flagging bogus errors ("Cannot find module 'fs' / 'path' / 'url'",
"Cannot find name 'process'"). Adds a minimal tsconfig that matches
tsx's runtime semantics: bundler resolution (so existing extensionless
relative imports keep working), ES2022 + DOM libs, Node types, strict
discriminated-union narrowing. Excludes __tests__/ to avoid surfacing
pre-existing type issues outside this PR's scope.
Jordan Ritter