Feishu Cli Write

This handles the full lifecycle of Feishu (Lark) document creation and updates through Markdown as an intermediate format. It shines when you need to programmatically generate docs with diagrams since Mermaid and PlantUML code blocks automatically convert to native Feishu boards. The incremental update system is smart: it has seven modes including replace_range for swapping specific sections by title, insert_before/after for precision edits, and delete_range, all designed to preserve inline comments and board references that would be lost with a full overwrite. It also handles the permissions dance automatically, supports callouts in six colors, and includes LaTeX math rendering. Worth noting it enforces UTF-8 validation checks and has specific Mermaid restrictions to avoid parser failures on the Feishu side.