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/api/v1/pdf.py

@@ -0,0 +1,52 @@
+import uuid
+from pathlib import Path
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.responses import FileResponse
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.api.deps import get_current_user
+from app.database import get_db
+from app.models.user import User
+from app.schemas.pdf import GeneratePdfRequest, PdfListResponse, PdfResponse
+from app.services import pdf_service
+
+router = APIRouter(prefix="/pdf", tags=["pdf"])
+
+
+@router.post("/compile", response_model=PdfResponse, status_code=status.HTTP_201_CREATED)
+async def compile_pdf(
+    data: GeneratePdfRequest,
+    user: Annotated[User, Depends(get_current_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    pdf = await pdf_service.generate_health_pdf(
+        db, user.id, data.title, data.document_ids or None, data.chat_id,
+    )
+    return PdfResponse.model_validate(pdf)
+
+
+@router.get("/", response_model=PdfListResponse)
+async def list_pdfs(
+    user: Annotated[User, Depends(get_current_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    pdfs = await pdf_service.get_user_pdfs(db, user.id)
+    return PdfListResponse(pdfs=[PdfResponse.model_validate(p) for p in pdfs])
+
+
+@router.get("/{pdf_id}/download")
+async def download_pdf(
+    pdf_id: uuid.UUID,
+    user: Annotated[User, Depends(get_current_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    pdf = await pdf_service.get_pdf(db, pdf_id, user.id)
+    if not pdf:
+        raise HTTPException(status_code=404, detail="PDF not found")
+    file_path = Path(pdf.storage_path)
+    if not file_path.exists():
+        raise HTTPException(status_code=404, detail="PDF file not found on disk")
+    media_type = "application/pdf" if file_path.suffix == ".pdf" else "text/html"
+    return FileResponse(path=str(file_path), filename=f"{pdf.title}.pdf", media_type=media_type)