feat: Seitenzahlen der Druckausgabe per --page-markers (P5)

- Erkennung: epub:type/role pagebreak (aria-label, title, Text) sowie
  Seitenanker-IDs page_47, page37, seite-12 und p17 (nur leere a/span)
- Ausgabe: visible = \[S. 123\], comment = <!-- S. 123 -->, none (Standard)
- keine Marker in Code; Marker in Überschriften als Absatz davor;
  Layout-Tabellen-Überschriften behalten ihre Seitenmarke
- Bericht: layout.page_markers; interne data-e2m-*-Attribute nie im HTML

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_styles.py

@@ -162,3 +162,25 @@ def test_p3_p7_html_styles(convert):
     assert '<div style="text-align: center">\n\nWidmung\n\n</div>' in text
     assert "Zweiter Absatz." in text and "Aldus" not in text  # base paragraph style is not repeated
     assert run.report["css"]["applied"]["style"] >= 5
+
+
+PAGES = ('<h1>K</h1><p>Ende Seite 89.</p><div aria-label="90" epub:type="pagebreak" id="page90" role="doc-pagebreak"/>'
+         '<p>Text<a id="page_12"/> weiter, <span id="page_13">Wort</span> und<a id="p14"/> fort.</p>'
+         '<p id="p15">Absatz mit Absatz-ID.</p><h2><a id="page_16"/>Kapitelanfang</h2><p>x</p><pre><a id="page_17"/>code</pre>'
+         '<table class="Head2"><tr><td class="sec_num"><a id="page_18"/>1.2</td><td>Tabellentitel</td></tr></table>')
+
+
+def test_p5_page_markers(convert):
+    none = convert(Book(docs=[Doc("c.xhtml", PAGES)])).chapter("001")
+    assert "S. 90" not in none and "S. 12" not in none
+    vis = convert(Book(docs=[Doc("c.xhtml", PAGES)]), "--page-markers", "visible")
+    text = vis.chapter("001")
+    assert "Ende Seite 89.\n\n\\[S. 90\\]" in text
+    assert "Text\\[S. 12\\] weiter, \\[S. 13\\]Wort und\\[S. 14\\] fort." in text
+    assert "S. 15" not in text  # paragraph id, not a page
+    assert "\\[S. 16\\]\n\n## Kapitelanfang" in text  # marker before the heading, not inside it
+    assert "```\ncode\n```" in text  # nothing inside code
+    assert "\\[S. 18\\]\n\n## 1.2 Tabellentitel" in text  # layout-table heading keeps the page
+    assert vis.report["layout"]["page_markers"] == 6
+    com = convert(Book(docs=[Doc("c.xhtml", PAGES)]), "--page-markers", "comment").chapter("001")
+    assert "<!-- S. 90 -->" in com and "Text<!-- S. 12 --> weiter" in com