fix: Befunde aus der QA-Prüfung (Prompt_Kontrolle.md)

- F1: Nicht beschreibbares Ausgabeziel liefert eine verständliche
  Meldung und Exit 1 statt "Interner Fehler" (Exit 4).
- F2: Anker von <dt id> stehen vor dem fett gesetzten Glossarbegriff
  statt innerhalb der **-Marker.
- F3: Formeln als <img src="*.svg"> erscheinen im Bericht mit
  origin "svg" statt "image".

Regressionstests für alle drei Befunde ergänzt.

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

tests/test_chapters.py

@@ -114,3 +114,11 @@ def test_layout_table_headings_are_recognized(convert):
     assert "# 3 Grundlagen" in text
     assert "## 3.1 Einführung" in text
     assert "<table" not in text
+
+
+def test_glossary_anchor_is_placed_before_bold_term(convert):
+    """QA-F2: the anchor of a <dt id> must not end up inside the bold markers."""
+    body = ('<h1>K</h1><p><a href="#g">API</a></p><section epub:type="glossary"><h2>Glossar</h2>'
+            '<dl><dt id="g">API</dt><dd>Schnittstelle.</dd></dl></section>')
+    text = convert(Book(docs=[Doc("c.xhtml", body)])).chapter("002")
+    assert '<a id="g"></a>**API:** Schnittstelle.' in text

tests/test_integration.py

@@ -124,3 +124,20 @@ def test_example_books_structural_invariants(convert, epub: Path):
     for m in report["media"]["files"]:
         assert (run.out / m["file"]).is_file()
     assert sum(c["stats"]["word_count"] for c in report["chapters"]) > 1000
+
+
+def test_unwritable_output_parent_gives_clear_error(convert, tmp_path):
+    """QA-F1: a permission problem at the target must not be reported as internal error (exit 4)."""
+    import os
+    import stat
+
+    parent = tmp_path / "readonly"
+    parent.mkdir()
+    os.chmod(parent, stat.S_IRUSR | stat.S_IXUSR)
+    try:
+        run = convert(simple_book(), out=parent / "ziel")
+    finally:
+        os.chmod(parent, stat.S_IRWXU)
+    assert run.rc == 1
+    assert "Interner Fehler" not in run.stderr
+    assert "nicht beschreibbar" in run.stderr or "Schreibfehler" in run.stderr

tests/test_math.py

@@ -97,3 +97,10 @@ def test_math_image_mode(convert):
     assert text.count("![") == 3  # svg + both formula images
     assert "<math" in text  # pure MathML without image is not lost
     assert any(w["code"] == "mathml-no-image" for w in run.report["warnings"])
+
+
+def test_svg_file_formula_is_reported_as_svg(convert):
+    """QA-F3: <img src="*.svg"> inside a formula container is an SVG formula in the report."""
+    report = convert(math_book()).report
+    origins = {f["origin"] for f in report["formulas"]["items"]}
+    assert "svg" in origins