style: improve writing style in system prompts and initialization docs

- Adopt IRC-inspired pragmatic writing style per CLAUDE.md
- Improve article diversity and word choice
- Simplify mermaid diagrams for better web readability
- Remove unnecessary explanations and redundant content

🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

Author: gerred