feat: add ai-writing-tropes skill from tropes.fyi (#1164)
Comprehensive catalog of AI writing patterns to avoid, organized into
six categories: word choice, sentence structure, paragraph structure,
tone, formatting, and composition. Each category has its own reference
file with examples and fixes.
https://claude.ai/code/session_01S1R6eHV1ftixGbx4sWGg8N
Co-authored-by: Claude <noreply@anthropic.com>