Auto-format Markdown files via pre-commit hook

[falkoschindler]

Motivation

Enforce consistent Markdown formatting across the project automatically via pre-commit, so documentation style stays uniform without manual effort.

Implementation

Add an mdformat hook to .pre-commit-config.yaml with:

• --wrap keep to preserve existing line wrapping
• --number to avoid enumerating all ordered list items with 1.
• mdformat-gfm plugin for GitHub-flavored Markdown support
• mdformat-simple-breaks plugin to keep --- for horizontal rules (instead of 70 underscores)
• .cursor/ directory excluded

Existing Markdown files have been auto-formatted by the hook.

Progress

• The implementation is complete.
• Test is not necessary.
• Documentation is not necessary.