Add code quality skill template

[Ruuudy1]

Changes:

• Adds skill-templates/code-quality/SKILL.md.
• Preserves cross-language Python and C# style rules using Documentation skill-template markers.
• Covers imports, subscription variables, comments, boolean layout, blank lines, and custom data reader error handling.

Validation:

• python skill-templates\\bundle-skills.py --validate-only
• python skill-templates\\bundle-skills.py --dry-run
• Checked the new file for em dashes, non-ASCII punctuation, and non-ASCII characters.