Phase 8: Customizable PDF Templates — locale support, admin editor, seed templates

Backend:
- PdfTemplate model with locale field + UNIQUE(name, locale) constraint
- Migration 007: pdf_templates table + template_id FK on generated_pdfs
- Template service: CRUD, Jinja2 validation, render preview with sample data
- Admin endpoints: CRUD /admin/pdf-templates + POST preview
- User endpoint: GET /pdf/templates (active templates list)
- pdf_service: resolves template from DB by ID or falls back to default
  for the appropriate locale
- AI generate_pdf tool accepts optional template_id
- Seed script + 4 HTML template files:
  - Basic Report (en/ru) — general-purpose report
  - Medical Report (en/ru) — health-focused with disclaimers

Frontend:
- Admin PDF templates page with editor, locale selector, live preview (iframe),
  template variables reference panel
- PDF page: template selector dropdown in generation form
- API clients for admin CRUD + user template listing
- Sidebar: admin templates link
- English + Russian translations

Also added Phase 9 (OAuth) and Phase 10 (Rate Limits) placeholders to GeneralPlan.

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

frontend/public/locales/en/translation.json

@@ -38,7 +38,8 @@
     "context": "Context",
     "skills": "Skills",
     "personal_context": "My Context",
-    "pdf": "PDF Reports"
+    "pdf": "PDF Reports",
+    "pdf_templates": "Templates"
   },
   "dashboard": {
     "welcome": "Welcome, {{name}}",
@@ -157,7 +158,29 @@
     "title": "PDF Reports",
     "generate": "Generate PDF",
     "title_placeholder": "Report title...",
-    "no_pdfs": "No PDF reports generated yet."
+    "no_pdfs": "No PDF reports generated yet.",
+    "template": "Template",
+    "default_template": "Default template"
+  },
+  "pdf_templates": {
+    "title": "PDF Templates",
+    "create": "Create Template",
+    "edit": "Edit Template",
+    "no_templates": "No templates yet.",
+    "default": "Default",
+    "inactive": "Inactive",
+    "name": "Name",
+    "locale": "Language",
+    "description": "Description",
+    "html_content": "HTML Template",
+    "preview": "Preview",
+    "variables_ref": "Template Variables Reference",
+    "var_title": "Report title",
+    "var_user_name": "User's full name",
+    "var_generated_at": "Generation timestamp",
+    "var_memories": "List of memory entries (category, title, content, importance)",
+    "var_documents": "List of documents (original_filename, doc_type, excerpt)",
+    "var_ai_summary": "AI-generated summary (optional)"
   },
   "admin_users": {
     "title": "User Management",

frontend/public/locales/ru/translation.json

@@ -38,7 +38,8 @@
     "context": "Контекст",
     "skills": "Навыки",
     "personal_context": "Мой контекст",
-    "pdf": "PDF отчёты"
+    "pdf": "PDF отчёты",
+    "pdf_templates": "Шаблоны"
   },
   "dashboard": {
     "welcome": "Добро пожаловать, {{name}}",
@@ -157,7 +158,29 @@
     "title": "PDF отчёты",
     "generate": "Сгенерировать PDF",
     "title_placeholder": "Название отчёта...",
-    "no_pdfs": "PDF отчёты ещё не создавались."
+    "no_pdfs": "PDF отчёты ещё не создавались.",
+    "template": "Шаблон",
+    "default_template": "Шаблон по умолчанию"
+  },
+  "pdf_templates": {
+    "title": "Шаблоны PDF",
+    "create": "Создать шаблон",
+    "edit": "Редактировать шаблон",
+    "no_templates": "Шаблонов пока нет.",
+    "default": "По умолчанию",
+    "inactive": "Неактивен",
+    "name": "Название",
+    "locale": "Язык",
+    "description": "Описание",
+    "html_content": "HTML шаблон",
+    "preview": "Предпросмотр",
+    "variables_ref": "Справка по переменным шаблона",
+    "var_title": "Заголовок отчёта",
+    "var_user_name": "Полное имя пользователя",
+    "var_generated_at": "Дата и время генерации",
+    "var_memories": "Список записей памяти (category, title, content, importance)",
+    "var_documents": "Список документов (original_filename, doc_type, excerpt)",
+    "var_ai_summary": "Резюме от ИИ (необязательно)"
   },
   "admin_users": {
     "title": "Управление пользователями",