Fix 82 discoverability gaps: expand agent-guide and Home element lists
Home.md:
- Expand Word elements from 6 to 18 (add Run, Header/Footer, Section,
Bookmark, Footnote, Hyperlink, Comment, TOC, Equation, Style, Field, SDT)
- Expand Excel elements from 5 to 13 (add Comment, Named Range, Picture,
Shape, Conditional Formatting, AutoFilter, Sparkline, Pivot Table)
- Expand PPT elements from 5 to 13 (add Connector, Group, Video, Equation,
Notes, Zoom, 3D Model, Theme)
- Fix watch description to include Word and Excel
agent-guide.md (comprehensive rewrite):
- Split add section into Word (19), Excel (14), PowerPoint (14) subsections
- Split set section into Word (14), Excel (11), PowerPoint (12) subsections
- Add view modes list (text, annotated, outline, stats, issues, html, svg)
- Add HTML/SVG preview tasks for all formats
- Add watch (live preview) task
- Add new "Advanced features" section: merge, CSV import, track changes,
document protection, formula evaluator, document properties, auto-correction,
path aliases
- Add new "AI integration" section: MCP, skills, install
- Add footnote/endnote query task