feat(frontend): bootstrap Vite + React 19 + TS strict toolchain (F0.1)

- Vite 8 / React 19 / TS 6 strict (noUncheckedIndexedAccess, no baseUrl deprecation)
- Tailwind 4 via @tailwindcss/vite (no PostCSS step)
- TanStack Query 5, react-router-dom 7, Recharts, clsx
- Vitest + Testing Library + jsdom for unit tests
- Playwright skeleton + first smoke spec (login redirect)
- ESLint flat config: typescript-eslint type-checked, react-hooks, react-refresh, prettier
- Prettier config (semi, single quotes, 100-col, lf)
- IBM Plex font @font-face declarations targeting /fonts/ (self-host, no CDN — OPSEC)

frontend/.prettierrc.json

@@ -0,0 +1,9 @@
+{
+  "semi": true,
+  "singleQuote": true,
+  "trailingComma": "all",
+  "printWidth": 100,
+  "tabWidth": 2,
+  "arrowParens": "always",
+  "endOfLine": "lf"
+}