feat(web): scaffold client-side rendered SPA foundation

- feat: initialize Vite project with React 19, React Router 8, TanStack
  Query, Ant Design 6, and Tailwind CSS 4
- feat: add Oxlint with React/TypeScript rules, strict TypeScript
  config, and layered CSS import order
- docs: add decision record for client-rendered Web foundation with
  React, Ant Design, and Tailwind CSS
- docs: create web roadmap defining architecture boundaries and deferred
  dependencies
- build: pin Node.js 24 in mise.toml

web/src/index.css

@@ -0,0 +1,13 @@
+@layer theme, base, antd, components, utilities;
+@import 'tailwindcss';
+
+html,
+body,
+#root {
+  min-width: 320px;
+  min-height: 100%;
+}
+
+body {
+  margin: 0;
+}