docs: per-client connect instructions for every mainstream agent

Claude Code, Cursor, Windsurf, VS Code Copilot agent mode, Gemini CLI,
Antigravity, Codex CLI, and a generic mcp-remote bridge for stdio-only
clients (Cline, Zed, JetBrains). Same hosted URL everywhere; OAuth or
Bearer key per client.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>