feat: migrate frontend from Vue 3 to React 18 with TanStack ecosystem

- Complete rewrite of frontend using React 18 + TypeScript in strict mode
- Implement TanStack Router for file-based routing matching URL structure
- Use TanStack Query for server state management with smart caching
- Replace Pinia stores with React Context API for auth and UI state
- Adopt Tailwind CSS + shadcn/ui components for consistent styling
- Switch from pnpm to Bun for faster package management and builds
- Configure Vite to support React, TypeScript, and modern tooling
- Create frontend.go with Go embed package for embedding dist/ in binary
- Implement comprehensive TypeScript interfaces (strict mode, no 'any' types)
- Add dark mode support throughout with Tailwind CSS dark: classes
- Set up i18n infrastructure (English translations included)
- Remove all Vue 3 code, components, stores, CSS, and assets
- Includes 18 new files with ~2000 lines of production-ready code

frontend/README.md

@@ -0,0 +1,183 @@
+# WOLK Frontend
+
+Modern React 18 SPA for WOLK file browser.
+
+## Tech Stack
+
+- **Framework:** React 18 + TypeScript
+- **Build Tool:** Vite
+- **Package Manager:** Bun
+- **Routing:** TanStack Router (file-based)
+- **Data Fetching:** TanStack React Query
+- **State Management:** Context API + custom hooks
+- **UI Components:** shadcn/ui (Radix UI + Tailwind CSS)
+- **Styling:** Tailwind CSS
+- **Internationalization:** i18next
+- **Notifications:** react-hot-toast
+- **Date Formatting:** dayjs
+
+## Getting Started
+
+### Prerequisites
+
+- **Bun** >=1.0 ([install](https://bun.sh))
+- **Node** >=24.0.0 (for Vite compatibility)
+- **Go backend** running on `localhost:8080`
+
+### Installation
+
+```bash
+cd frontend
+bun install
+```
+
+### Development
+
+```bash
+# Start dev server (http://localhost:5173)
+bun run dev
+
+# In another terminal, start Go backend
+cd ..
+go run . --http :8080
+```
+
+Dev server automatically proxies `/api` to `http://localhost:8080`.
+
+### Building
+
+```bash
+# Full build with type-checking
+bun run build
+
+# Type-check only
+bun run typecheck
+
+# Lint
+bun run lint
+bun run lint:fix
+
+# Format
+bun run format
+
+# Clean dist
+bun run clean
+```
+
+## Project Structure
+
+```
+src/
+├── api/                    # API client modules (files, auth)
+├── components/
+│   ├── ui/                 # shadcn UI components
+│   ├── layout/             # Header, Sidebar, LayoutShell
+│   ├── files/              # File-related components
+│   └── modals/             # Dialog components
+├── context/                # React Context (Auth, Layout)
+├── hooks/                  # Custom React hooks (useFiles, useAuth, etc.)
+├── routes/                 # TanStack Router file-based routes
+├── types/                  # TypeScript interfaces
+├── utils/                  # Utility functions (format, constants, etc.)
+├── i18n/                   # i18next translations
+├── lib/                    # Library setup (QueryClient, etc.)
+├── styles/                 # Global CSS
+├── main.tsx                # Entry point
+└── App.tsx                 # Root component
+```
+
+## Coding Standards
+
+See `AGENTS.md` in the project root for detailed style guidelines.
+
+### Key Patterns
+
+**Custom Hooks (TanStack Query)**
+```tsx
+const { data, isPending, error } = useFiles(path);
+```
+
+**Components**
+```tsx
+interface FileListingProps {
+  path: string;
+  onFileSelect?: (file: IFile) => void;
+}
+
+export function FileListing({ path, onFileSelect }: FileListingProps) {
+  // Component logic
+}
+```
+
+**Routes**
+```tsx
+export const Route = createFileRoute("/files/$path")({
+  component: FileListingPage,
+  loader: async ({ params }) => {
+    // Pre-fetch data
+  },
+});
+```
+
+**Error Handling**
+```tsx
+const { showError } = useToast();
+try {
+  await apiCall();
+} catch (err) {
+  if (err instanceof ApiError && err.isCanceled) return; // silent
+  showError(err);
+}
+```
+
+## API Client
+
+The API client is located in `src/api/` with automatic:
+- Token injection in `X-Auth` header
+- Error handling with `ApiError` class
+- Auto-logout on 401
+- Request cancellation support
+
+```ts
+import { files as fileAPI } from "@/api";
+
+const files = await fileAPI.fetchFiles("/documents");
+```
+
+## Translations
+
+Translations are in `src/i18n/en.json`. To add support for more languages:
+
+1. Create `src/i18n/{lang}.json` with translations
+2. Update `src/i18n/config.ts` to include the new language
+
+```ts
+import langTranslations from "./{lang}.json";
+
+resources: {
+  {lang}: { translation: langTranslations },
+}
+```
+
+## Testing
+
+Frontend testing infrastructure is not yet configured. Future: Vitest for unit tests, Playwright for e2e.
+
+For now, use `bun run typecheck` for type validation.
+
+## Contributing
+
+1. Follow the code style guidelines in `AGENTS.md`
+2. Use `bun run lint:fix && bun run format` before committing
+3. Ensure `bun run typecheck` passes
+4. Create reusable components in `src/components/`
+5. Use TanStack Query for all server state
+
+## Resources
+
+- [TanStack React Query](https://tanstack.com/query/latest)
+- [TanStack Router](https://tanstack.com/router/latest)
+- [shadcn/ui](https://ui.shadcn.com)
+- [Tailwind CSS](https://tailwindcss.com)
+- [i18next](https://www.i18next.com)
+- [Vite](https://vitejs.dev)