Phase 6: PDF & Polish — PDF generation, admin users/settings, AI tool

Backend:
- Setting + GeneratedPdf models, Alembic migration with default settings seed
- PDF generation service (WeasyPrint + Jinja2 with autoescape)
- Health report HTML template with memory entries + document excerpts
- Admin user management: list, create, update (role/max_chats/is_active)
- Admin settings: self_registration_enabled, default_max_chats
- Self-registration check wired into auth register endpoint
- default_max_chats applied to new user registrations
- AI tool: generate_pdf creates health compilation PDFs
- PDF compile/list/download API endpoints
- WeasyPrint system deps added to Dockerfile

Frontend:
- PDF reports page with generate + download
- Admin users page with create/edit/activate/deactivate
- Admin settings page with self-registration toggle + max chats
- Extended sidebar with PDF reports + admin users/settings links
- English + Russian translations for all new UI

Review fixes applied:
- Jinja2 autoescape enabled (XSS prevention in PDFs)
- db.refresh after flush (created_at populated correctly)
- storage_path removed from API response (no internal path leak)
- Role field uses Literal["user", "admin"] validation
- React hooks called before conditional returns (rules of hooks)
- default_max_chats setting now applied during registration

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/public/locales/en/translation.json

@@ -37,7 +37,8 @@
     "users": "Users",
     "context": "Context",
     "skills": "Skills",
-    "personal_context": "My Context"
+    "personal_context": "My Context",
+    "pdf": "PDF Reports"
   },
   "dashboard": {
     "welcome": "Welcome, {{name}}",
@@ -152,6 +153,27 @@
       "low": "Low"
     }
   },
+  "pdf": {
+    "title": "PDF Reports",
+    "generate": "Generate PDF",
+    "title_placeholder": "Report title...",
+    "no_pdfs": "No PDF reports generated yet."
+  },
+  "admin_users": {
+    "title": "User Management",
+    "create": "Create User",
+    "edit": "Edit User",
+    "max_chats": "Max Chats",
+    "deactivate": "Deactivate",
+    "activate": "Activate"
+  },
+  "admin_settings": {
+    "title": "App Settings",
+    "self_registration": "Self Registration",
+    "self_registration_desc": "Allow users to register accounts themselves",
+    "default_max_chats": "Default Max Chats",
+    "default_max_chats_desc": "Default chat limit for new users"
+  },
   "common": {
     "loading": "Loading...",
     "error": "An error occurred",

frontend/public/locales/ru/translation.json

@@ -37,7 +37,8 @@
     "users": "Пользователи",
     "context": "Контекст",
     "skills": "Навыки",
-    "personal_context": "Мой контекст"
+    "personal_context": "Мой контекст",
+    "pdf": "PDF отчёты"
   },
   "dashboard": {
     "welcome": "Добро пожаловать, {{name}}",
@@ -152,6 +153,27 @@
       "low": "Низкая"
     }
   },
+  "pdf": {
+    "title": "PDF отчёты",
+    "generate": "Сгенерировать PDF",
+    "title_placeholder": "Название отчёта...",
+    "no_pdfs": "PDF отчёты ещё не создавались."
+  },
+  "admin_users": {
+    "title": "Управление пользователями",
+    "create": "Создать пользователя",
+    "edit": "Редактировать пользователя",
+    "max_chats": "Макс. чатов",
+    "deactivate": "Деактивировать",
+    "activate": "Активировать"
+  },
+  "admin_settings": {
+    "title": "Настройки приложения",
+    "self_registration": "Самостоятельная регистрация",
+    "self_registration_desc": "Разрешить пользователям самим создавать аккаунты",
+    "default_max_chats": "Лимит чатов по умолчанию",
+    "default_max_chats_desc": "Лимит чатов для новых пользователей"
+  },
   "common": {
     "loading": "Загрузка...",
     "error": "Произошла ошибка",