Move supported features from matrix to individual client sections

Remove the feature support matrix table and consolidate feature
information into each client's detail section with a "Supports:" line.
This improves readability by keeping all client information together.

Also add missing description for Gemini CLI entry, and fix Zencoder link
(`https://zecoder.ai` => `https://zencoder.ai`).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: jonathanhefner