feat: add md-to-docx-plus skill with LaTeX equation support

Add a new skill that converts Markdown to Word (.docx) with editable
OMML math equations. Unlike the existing md-to-docx skill (JavaScript),
this uses Python (python-docx + latex2word + latex2mathml) to convert
LaTeX math expressions ($inline$ and $$display$$) into native Word
equations that are fully editable in Word's equation editor.

Supports: fractions, subscripts, superscripts, roots, summations,
integrals, matrices, Greek letters, limits, and more.

Author: George-Chia

skills/md-to-docx-plus/SKILL.md

@@ -0,0 +1,87 @@
+---
+name: md-to-docx-plus
+description: "Convert Markdown files to Word (.docx) with editable OMML math equations. Handles LaTeX formulas ($...$ and $$...$$), producing natively editable equations in Word. Use this skill whenever converting markdown to docx where the content contains math formulas, equations, scientific notation, or LaTeX expressions — even if the user just says 'convert this md to docx' and the file might contain math."
+---
+
+# Markdown to Word (.docx) with Editable Equations
+
+Convert Markdown (`.md`) files into professionally formatted Word (`.docx`) documents with **editable OMML equations** derived from LaTeX math notation. Uses Python (`python-docx` + `latex2word` + `latex2mathml`) — no Pandoc, LibreOffice, or MS Office required.
+
+The key difference from `md-to-docx`: LaTeX math expressions (`$inline$` and `$$display$$`) are converted into **native Word OMML equations** that are fully editable in Word's equation editor — not images, not plain text.
+
+## How to Convert
+
+```bash
+# Install dependencies (one-time)
+pip install python-docx latex2word latex2mathml lxml
+
+# Convert (run from workspace root)
+python3 skills/md-to-docx-plus/scripts/md_to_docx_plus.py <input.md> [output.docx]
+```
+
+If `output.docx` is omitted, it defaults to `<input-basename>.docx`.
+
+## Skill Folder Contents
+
+| File | Purpose |
+|------|---------|
+| `SKILL.md` | This instruction file |
+| `scripts/md_to_docx_plus.py` | Python Markdown-to-Word converter with equation support |
+| `scripts/requirements.txt` | Python dependencies |
+
+## Prerequisites
+
+| Requirement | Version | Notes |
+|-------------|---------|-------|
+| **Python** | 3.10+ | Required runtime |
+| **python-docx** | 1.1+ | Word document generation |
+| **latex2word** | 1.0+ | LaTeX to OMML conversion |
+| **latex2mathml** | 3.77+ | LaTeX to MathML (used by latex2word) |
+| **lxml** | 5.0+ | XML processing |
+
+Works on Windows, macOS, and Linux. No system-level installs beyond Python packages.
+
+## Features
+
+The converter:
+
+- **Converts LaTeX math to editable Word equations** — `$inline$` and `$$display$$` notation becomes native OMML
+- **Extracts YAML front-matter** — uses `title`, `date`, `version`, `audience` for the title page
+- **Generates a title page** — with project name, subtitle, date, version, and audience
+- **Generates a table of contents** — built from H1-H3 headings
+- **Embeds PNG images** — resolves `![alt](path)` references relative to the input `.md` file
+- **Styled output** — Calibri body, Cambria Math for equations, Consolas for code, colored headings
+- **Handles all Markdown elements** — headings, paragraphs, tables, code blocks, lists, images, links, horizontal rules
+
+## LaTeX Math Support
+
+Inline math uses single `$...$`:
+
+```markdown
+The loss function $L = -\sum_{i} y_i \log(\hat{y}_i)$ measures cross-entropy.
+```
+
+Display (block) math uses double `$$...$$`:
+
+```markdown
+$$
+\theta_{t+1} = \theta_t - \alpha \nabla_\theta J(\theta)
+$$
+```
+
+Both produce **editable OMML equations** in Word — click to edit, same as inserting an equation via Word's ribbon.
+
+Supported LaTeX constructs: fractions, subscripts, superscripts, square roots, summations, integrals, matrices, piecewise functions, Greek letters, operators, limits, and more.
+
+## Front-Matter Format
+
+```yaml
+---
+title: Project Name — Project Summary
+date: 2025-01-15
+version: 1.0
+audience: Engineering Team
+---
+```
+
+The title is split on `—` or `–` into main title and subtitle for the title page.