docs: add SDK integration prompt for WarpGrep TypeScript SDK

Mirrors the existing Python integration prompt with full coverage for
the @morphllm/morphsdk package — provider examples (Anthropic, OpenAI,
Vercel AI SDK, Gemini), streaming, GitHub search, sandbox/remoteCommands,
and layered test suite.

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