feat: uv config other feats

- add uv configuration for the backend
- update frontend to make auth work
- add new auth endpoints
- add bookmars feat
- add reader feat

docs/frontend/013-i18n-web.md

@@ -0,0 +1,54 @@
+# 013 — Frontend i18n (react-i18n-lite)
+
+**Status:** Implemented  
+**Created:** 2026-06-04
+
+## Objective
+
+Internationalize the web UI in English (`en-US`) and Spanish (`es-ES`) using [react-i18n-lite](https://www.npmjs.com/package/react-i18n-lite).
+
+## Architecture
+
+```
+App.tsx
+  └── I18nProvider (TranslationContainer)
+        ├── resolveDefaultLanguage() — localStorage → navigator → en-US
+        ├── LanguagePersistence — sync setLanguage ↔ localStorage, html[lang]
+        └── AuthProvider → ToastProvider → routes
+```
+
+Components call `useTranslation()` and `t('namespace.key', { interpolation })`.
+
+## Locale files
+
+| File | Purpose |
+|------|---------|
+| `frontend/src/locales/en-US.ts` | English dictionary |
+| `frontend/src/locales/es-ES.ts` | Spanish dictionary |
+| `frontend/src/locales/index.ts` | `locales` map, `SupportedLanguage`, helpers |
+
+Key namespaces: `common`, `auth`, `library`, `contextMenu`, `toast`, `settings`, `reader`, `addBook`, `bookDetail`, `search`, `annotations`.
+
+## Language selection
+
+- **Settings page** — UI Language dropdown (English / Español)
+- **Persistence** — `localStorage` key `cloud-reader.locale`
+- **Default** — saved preference, else `navigator.language` (`es*` → `es-ES`), else `en-US`
+
+## Scope
+
+**Translated:** All user-facing chrome (library, auth, reader toolbar/settings/TOC, add book, book detail, annotations, context menu, toasts).
+
+**Not translated:** EPUB body content, API error bodies, backend `reading_status_display`, Open Library metadata fields.
+
+## Dependencies
+
+- `react-i18n-lite` (^1.0.10)
+
+## Verification
+
+1. Open app — labels match browser or saved language
+2. Settings → switch to Español — library/auth update without reload
+3. Refresh — language persists
+4. Context menu and toasts show translated strings
+5. `yarn build` succeeds