[marketing] Add Chinese content quality / anti-AI-slop skill

The marketing plugin currently has great skills for content creation, campaign planning, and SEO — but nothing for content quality control, especially for non-English content.

Chinese AI-generated content has distinct telltale patterns that are different from English (different filler phrases, punctuation habits, structural clichés). As more teams use Claude for Chinese content marketing, a quality check skill would be valuable.

I've built an open-source skill for this: stop-slop-zh

It includes:

• 30+ banned Chinese AI filler phrases
• Punctuation rules specific to Chinese typography (AI overuses colons, em-dashes, double quotes)
• 50+ recommended colloquial expressions for natural voice
• 4-layer quality check system (hard rules → style → content → human-feel)
• Before/after transformation examples

Happy to adapt this into the plugin format if the team thinks it's a good fit for the marketing plugin. Could also work as a standalone content-quality or localization plugin.