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>

backend/app/services/ai_service.py

@@ -92,6 +92,17 @@ AI_TOOLS = [
             "required": ["title", "body"],
         },
     },
+    {
+        "name": "generate_pdf",
+        "description": "Generate a PDF health report compilation from the user's data. Use this when the user asks for a document or summary of their health information.",
+        "input_schema": {
+            "type": "object",
+            "properties": {
+                "title": {"type": "string", "description": "Title for the PDF report"},
+            },
+            "required": ["title"],
+        },
+    },
 ]
 
 
@@ -161,6 +172,17 @@ async def _execute_tool(
             "title": notif.title,
         })
 
+    elif tool_name == "generate_pdf":
+        from app.services.pdf_service import generate_health_pdf
+        pdf = await generate_health_pdf(db, user_id, title=tool_input["title"])
+        await db.commit()
+        return json.dumps({
+            "status": "generated",
+            "id": str(pdf.id),
+            "title": pdf.title,
+            "download_url": f"/api/v1/pdf/{pdf.id}/download",
+        })
+
     return json.dumps({"error": f"Unknown tool: {tool_name}"})