Add Word-validation test fixtures generated by the real formatter

tests/make_word_test_files.py regenerates three fixtures:
- tests/word_test_input.docx   - tagged mini manuscript (book start through
  req review, all section roles, <<<>>> scene breaks)
- tests/word_test_output.docx  - output of format_document() on the above
- tests/python_docx_control.docx - untouched python-docx save (baseline)

Purpose: bisect the Word-open failure. The full manuscript output is
structurally clean by every OOXML check (package rels, content types,
sectPr/settings ordering, header/footer parts, fields, hyperlinks, custom
parts all validate); the fixtures let Word itself tell us whether the
pipeline or the manuscript content is the trigger.

.gitignore

@@ -12,6 +12,7 @@ umbraformat/formatted/
 
 # Documents / user scratch files (not part of the app source)
 *.docx
+!tests/*.docx
 summary.txt
 Sections_Tags
 Word_to_PDF_print_formatting

tests/make_word_test_files.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+"""Regenerate the Word-validation test fixtures.
+
+Builds a small but complete manuscript that exercises the real formatting
+rules (book start -> titlepage/copyright/dedication/epigraph/TOC/prologue/
+chapters with <<<>>> scene breaks -> back matter / about author / req review),
+runs it through format_document(), and writes:
+
+  tests/word_test_input.docx     - the tagged source manuscript
+  tests/word_test_output.docx    - the FORMATTED DOCX to try in Word
+  tests/python_docx_control.docx - plain python-docx save (Word baseline)
+
+Usage: .venv/bin/python tests/make_word_test_files.py
+"""
+
+import os
+import sys
+import tempfile
+
+from docx import Document
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from umbraformat.formatter import format_document
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+
+
+def build_manuscript(path):
+    """Minimal tagged manuscript mirroring the real book section structure."""
+    d = Document()
+    paras = [
+        "[book start]",
+        "Sidney and Watson: Test Edition",
+        "A Formatting Validation Novella",
+        "B.D. Murphy",
+        "[copyright]",
+        "Copyright 2026 by B.D. Murphy. All rights reserved.",
+        "Published by WorstAuthor LLC. No part of this publication may be "
+        "reproduced in any form without the prior written permission of the "
+        "publisher.",
+        "[dedication]",
+        "For every tester who ever bravely opened a broken file.",
+        "[epigraph]",
+        "\u201cThe formatting rules are the worst ones.\u201d \u2014 The Editor",
+        "[TOC]",
+        "[prologue]",
+        "Prologue \u2014 Some time before the story, the investigation had "
+        "already begun in earnest.",
+        "The second prologue paragraph crossed the gutter calmly and expected "
+        "no indent on its first line.",
+        "[chapter]",
+        "Chapter One: The Beginning",
+        "It was the best of times in the kingdom of formatting. Every page was "
+        "justified, every heading kept with next, and every footer held its "
+        "page number centered in the gutter-safe zone.",
+        "The second paragraph indents on its first line because the paragraph "
+        "above it required no indent at all.",
+        "<<<>>>",
+        "After the scene break, the action resumed with fresh urgency and a "
+        "brand new paragraph of prose.",
+        "[chapter]",
+        "Chapter Two: The Middle",
+        "The middle chapter advanced the plot through mirrored margins, odd "
+        "page starts, and lowercase roman numerals in the front matter.",
+        "A further paragraph of supporting text kept the chapter from ending "
+        "too soon, ensuring the running head had room to breathe.",
+        "[chapter]",
+        "Chapter Three: The Revelation",
+        "The final chapter revealed the truth: the document opens in Word, "
+        "and that is all that matters.",
+        "<<<>>>",
+        "A closing scene break, then a short denouement paragraph.",
+        "And then the story was over, except for the back matter.",
+        "[back matter]",
+        "Appendix: The Appendix",
+        "Reference material of a lengthy and largely optional nature.",
+        "[about author]",
+        "The author lives in a small town and writes at night.",
+        "[req review]",
+        "Reviewer: structure verified, page numbers centered, headers title-"
+        "only, scene breaks preserved.",
+    ]
+    for text in paras:
+        d.add_paragraph(text)
+    d.save(path)
+
+
+def build_control(path):
+    """Untouched python-docx document: does Word open this at all?"""
+    d = Document()
+    d.add_paragraph("Hello Word. This is a plain python-docx control document.")
+    d.add_paragraph("If this opens but the formatted test file does not, the "
+                    "problem is in the formatting pipeline, not python-docx.")
+    d.save(path)
+
+
+def main():
+    with tempfile.TemporaryDirectory(prefix="umbraformat_word_test_") as tmp:
+        src = os.path.join(tmp, "manuscript.docx")
+        out = os.path.join(tmp, "formatted.docx")
+        build_manuscript(src)
+        format_document(
+            src,
+            out,
+            font_name="Caladea",
+            font_size=11,
+            inner_margin=0.50,
+            trim_size="5.5x8.5",
+            author="B.D. Murphy",
+            imprint="WorstAuthor LLC",
+            strip_problematic_graphics=True,
+            language="en",
+        )
+        shutil.copy(src, os.path.join(HERE, "word_test_input.docx"))
+        shutil.copy(out, os.path.join(HERE, "word_test_output.docx"))
+    build_control(os.path.join(HERE, "python_docx_control.docx"))
+    print("wrote tests/word_test_input.docx, tests/word_test_output.docx, "
+          "tests/python_docx_control.docx")
+
+
+if __name__ == "__main__":
+    import shutil
+
+    main()