Implementace prevodu HTML na PDF

Sluzba prijme adresu HTML dokumentu nebo HTML v tele requestu a vrati PDF.
Navrzena pro dokumenty o stovkach az tisicich stranek.

Rendering:
- WeasyPrint jako vychozi engine, spravne CSS Paged Media, nizka pametova
  narocnost, bez JavaScriptu
- Chromium pres Playwright pro dokumenty dokreslovane skripty
- rezim auto s detekci skriptu a fallbackem pri selhani WeasyPrintu

Velke dokumenty:
- deleni na casti na strukturalnich hranicich, rez nikdy uvnitr tabulky
  nebo odstavce
- dvoupruchodovy render obsahu se skutecnymi cisly stranek, pozice nadpisu
  se ctou z kotev hlasenych u kazde stranky
- cislovani stranek bud pres CSS countery, nebo pres cislovaci vrstvu
  nastampovanou na hotove PDF, rozmer stranky se cte z vysledneho souboru
- Chromium se restartuje po N jobech, nikdy vsak behem beziciho renderu

API:
- POST /convert synchronne, POST /jobs asynchronne se sledovanim stavu,
  stahovanim vysledku, rusenim a volitelnym callbackem
- GET /health s overenim dostupnosti obou enginu a stavem fronty
- OpenAPI respektuje prefix reverse proxy pres root_path

Bezpecnost a provoz:
- SSRF kontrola po DNS resolvu, na kazdem presmerovani a u vsech pozadavku
  prohlizece
- nedostupne assety render nezastavi, ale hlasi se v odpovedi i v logu
- fronta s omezenym poctem workeru, rozpracovane joby se pri ukonceni
  oznaci jako failed, nezmizi potichu
- strukturovane JSON logovani s job_id
- vsechny limity vypnute ve vychozim stavu

Dockerfile je dvoufazovy, obsahuje zavislosti WeasyPrintu, Chromium
a fonty s ceskou diakritikou.

Autentizace zamerne neni implementovana, zpusob predavani neni domluveny.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/routers/jobs.py

@@ -0,0 +1,90 @@
+"""Asynchronous conversion. This is the path for large documents."""
+
+from __future__ import annotations
+
+import logging
+
+from fastapi import APIRouter, Response, status
+from fastapi.responses import FileResponse
+
+from ..deps import get_container
+from ..errors import ConversionError, JobNotFoundError
+from ..models import ConvertRequest, JobAccepted, JobState
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/jobs", tags=["joby"])
+
+
+def _result_url(job_id: str) -> str:
+    root = get_container().settings.root_path.rstrip("/")
+    return f"{root}/jobs/{job_id}/result"
+
+
+@router.post(
+    "",
+    response_model=JobAccepted,
+    status_code=status.HTTP_202_ACCEPTED,
+    summary="Zaradi konverzi do fronty",
+)
+async def create_job(request: ConvertRequest) -> JobAccepted:
+    job = get_container().jobs.submit(request)
+    return JobAccepted(
+        job_id=job.id,
+        status=job.state.status,
+        created_at=job.state.created_at,
+        result_url=_result_url(job.id),
+    )
+
+
+@router.get("/{job_id}", response_model=JobState, summary="Stav jobu")
+async def job_state(job_id: str) -> JobState:
+    job = get_container().jobs.get(job_id)
+    state = job.state.model_copy()
+    if state.status == "done":
+        state.result_url = _result_url(job_id)
+    return state
+
+
+@router.get(
+    "/{job_id}/result",
+    summary="Stahne hotove PDF",
+    response_class=Response,
+    responses={
+        200: {"content": {"application/pdf": {}}, "description": "Hotove PDF."},
+        404: {"description": "Job neexistuje nebo uz expiroval."},
+        409: {"description": "Job jeste nedobehl nebo skoncil chybou."},
+    },
+)
+async def job_result(job_id: str):
+    container = get_container()
+    job = container.jobs.get(job_id)
+
+    if job.state.status != "done":
+        error = ConversionError(
+            f"Vysledek neni k dispozici, job je ve stavu {job.state.status}.",
+            {"status": job.state.status},
+        )
+        error.error_code = "result_not_ready"
+        error.status_code = 409
+        raise error
+
+    path = container.storage.result_path(job_id)
+    if not path.exists():
+        raise JobNotFoundError("Soubor s vysledkem uz neexistuje, job pravdepodobne expiroval.")
+
+    filename = job.request.filename or "dokument.pdf"
+    return FileResponse(
+        path,
+        media_type="application/pdf",
+        filename=filename,
+        headers={
+            "X-Page-Count": str(job.state.page_count or 0),
+            "X-Engine-Used": job.state.engine_used or "",
+        },
+    )
+
+
+@router.delete("/{job_id}", response_model=JobState, summary="Zrusi job nebo smaze jeho vysledek")
+async def delete_job(job_id: str) -> JobState:
+    return get_container().jobs.cancel(job_id).state