Ultra-Long Feasibility Report Multi-Agent Collaborative Writing v3.3

Changelog (v3.3)

✅ Table parsing fully fixed (_flush_table not calling _parse_md_table caused character-by-character splitting)
✅ Colorful chapter headings officially launched (H1 deep navy full-row band / H2 medium blue block / H3 light blue left bar)
✅ Styled tables launched (deep blue header + white text + alternating row colors)
✅ Key callout boxes launched (【关键】【注意】【优势】【风险】【数据】 color-coded cards)
✅ Cover style enhanced (tech-digital style deep ocean blue full-screen background + white text)
✅ Cover/Contents/Executive Summary title bars all colored
✅ Fixed cover_style integer vs string comparison preventing cover from applying
✅ Fixed RGBColor.from_string() instead of eval to avoid type errors