Add guidance to avoid whitespace reformatting in docx/ooxml skill

[thejud]

Using the docx skill to add a comment to a word doc resulted in a document unreadable by word (and by soffice/libreoffice). Pandoc could extract the content. After some investigation, claude figured out that it was formatting the document incorrectly by adding additional whitespace.

It provided the following additional guidance to refine the ooxml prompt. I'm happy to include this as a PR, but suspect you are extremely particular about tuning the prompt, so I'll provide what is working for me:

For complex scenarios not covered by the library:

**CRITICAL: XML Serialization**
When writing XML back to files after manipulation with defusedxml.minidom, you MUST preserve the original formatting:
- ✅ **USE**: `doc.toxml(encoding='utf-8')` - Preserves original formatting, Word-compatible
- ❌ **NEVER USE**: `doc.toprettyxml()` - Adds extra whitespace that breaks Word compatibility

Microsoft Word is extremely sensitive to XML whitespace. Using `toprettyxml()` adds newlines and indentation that Word interprets as part of the document structure, causing documents to become unreadable. Always use `toxml()` to maintain the compact format Word expects.

and

# CRITICAL: When writing XML manually (not using Document class)
# ✅ CORRECT - preserves formatting:
with open(doc_path, 'wb') as f:
    f.write(doc.toxml(encoding='utf-8'))

# ❌ WRONG - breaks Word compatibility:
with open(doc_path, 'wb') as f:
    f.write(doc.toprettyxml(indent='  ', encoding='utf-8'))

[thejud]

Here is an example of the prompt I used that generated invalid docs. The initial doc is valid, but after adding the comment, the document is unreadable by word. Updating the prompt as in the description fixes the issue for met.

Create a concise guide to uv with several png images: one of the file tree and the uv logo. Write it in docx format to /tmp/uv.docx. Then make a copy of that document, and add a comment on a line in the first several paragraphs, for example, to simplify the header line.

[cdxiaodong]

pr-link:#143

[dechapon25]

นี่คือตัวอย่างของข้อความแจ้งเตือนที่ฉันใช้ซึ่งทำให้เอกสารไม่ถูกต้อง เอกสารเริ่มต้นนั้นถูกต้อง แต่หลังจากเพิ่มความคิดเห็นแล้ว เอกสารนั้นอ่านไม่ได้ด้วยโปรแกรม Word การแก้ไขข้อความแจ้งเตือนตามคำอธิบายช่วยแก้ปัญหานี้ได้

Create a concise guide to uv with several png images: one of the file tree and the uv logo. Write it in docx format to /tmp/uv.docx. Then make a copy of that document, and add a comment on a line in the first several paragraphs, for example, to simplify the header line.

[dechapon25]

การแจ้งเตือนข้อความที่เน้นย้ำถึงเอกสารที่เป็นเอกสารเริ่มต้นนั้นถูกต้อง แต่หลังจากเพิ่มความคิดเห็นแล้วเอกสารนั้นอ่านไม่ได้โปรแกรมด้วย Word จริงข้อความแจ้งเตือนตามคำอธิบายช่วยแก้ปัญหานี้

Create a concise guide to uv with several png images: one of the file tree and the uv logo. Write it in docx format to /tmp/uv.docx. Then make a copy of that document, and add a comment on a line in the first several paragraphs, for example, to simplify the header line.