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>

tests/conftest.py

@@ -0,0 +1,46 @@
+"""Shared fixtures.
+
+Nothing here starts a real browser. Engine level tests skip themselves when the
+engine is not installed in the current environment.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+
+def build_document(sections: int, paragraphs_per_section: int = 12) -> str:
+    """Synthetic document with predictable structure and size."""
+    parts = [
+        "<!DOCTYPE html><html><head><meta charset='utf-8'>",
+        "<style>body{font-family:sans-serif;font-size:11pt}</style>",
+        "</head><body>",
+    ]
+    for index in range(sections):
+        parts.append(f"<section id='sekce-{index}'><h1>Kapitola {index + 1}</h1>")
+        for paragraph in range(paragraphs_per_section):
+            parts.append(
+                f"<p>Odstavec {paragraph + 1} kapitoly {index + 1}. "
+                + ("Text s ceskou diakritikou pro overeni fontu. " * 8)
+                + "</p>"
+            )
+        parts.append("</section>")
+    parts.append("</body></html>")
+    return "".join(parts)
+
+
+@pytest.fixture
+def small_document() -> str:
+    return build_document(sections=3, paragraphs_per_section=2)
+
+
+@pytest.fixture
+def large_document() -> str:
+    """Roughly twelve hundred pages, used for memory and timing measurements."""
+    return build_document(sections=400, paragraphs_per_section=14)
+
+
+@pytest.fixture
+def unsplittable_document() -> str:
+    body = "".join(f"<p>Odstavec {index}. " + ("Text. " * 40) + "</p>" for index in range(200))
+    return f"<!DOCTYPE html><html><head><meta charset='utf-8'></head><body>{body}</body></html>"