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/eslint.config.js

@@ -0,0 +1,54 @@
+import js from '@eslint/js';
+import globals from 'globals';
+import reactHooks from 'eslint-plugin-react-hooks';
+import reactRefresh from 'eslint-plugin-react-refresh';
+import tseslint from 'typescript-eslint';
+import prettier from 'eslint-config-prettier';
+import { defineConfig, globalIgnores } from 'eslint/config';
+
+export default defineConfig([
+  globalIgnores([
+    'dist',
+    'coverage',
+    'playwright-report',
+    'test-results',
+    'node_modules',
+    'e2e/**',
+    'playwright.config.ts',
+    'vitest.config.ts',
+    'vite.config.ts',
+  ]),
+  {
+    files: ['**/*.{ts,tsx}'],
+    extends: [
+      js.configs.recommended,
+      tseslint.configs.recommendedTypeChecked,
+      reactHooks.configs.flat.recommended,
+      reactRefresh.configs.vite,
+      prettier,
+    ],
+    languageOptions: {
+      globals: globals.browser,
+      parserOptions: {
+        projectService: true,
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+    rules: {
+      'react-hooks/exhaustive-deps': 'error',
+      '@typescript-eslint/consistent-type-imports': ['error', { prefer: 'type-imports' }],
+      '@typescript-eslint/no-floating-promises': 'error',
+      '@typescript-eslint/no-misused-promises': 'error',
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        { argsIgnorePattern: '^_', varsIgnorePattern: '^_' },
+      ],
+    },
+  },
+  {
+    files: ['**/*.test.{ts,tsx}', 'src/test/**'],
+    rules: {
+      '@typescript-eslint/no-floating-promises': 'off',
+    },
+  },
+]);