Enhancement: Add AI-assisted development guide

A new guide has been added to the oCIS documentation demonstrating how to build
web extensions using AI-assisted development with Claude AI. The guide covers
MCP connector setup, a five-phase development workflow, debugging techniques,
and contribution workflows.

This approach has been validated through real contributions including PR #11912
(photo metadata search backend) and web extensions PRs #305 and #306.

https://github.com/owncloud/ocis/pull/11941
