docs: comprehensive README with all 9 IDE integrations

Complete rewrite of README covering introduction, features, prerequisites,
setup guides for Cursor, VS Code, Claude Code, Claude Desktop, Windsurf,
Gemini CLI, Gemini Code Assist, Opencode, Zapier, and ElevenLabs. Includes
usage examples, self-hosting instructions, full tool reference table,
roadmap, contributing guidelines, and MIT license.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: 2 people