feat: add Chroma Package Search WarpGrep example

Routes all three WarpGrep remote commands (grep, read, listDir) through
Chroma's Package Search MCP API. No sandbox VM needed — searches any of
3,000+ indexed public packages across npm, PyPI, crates.io, and Go proxy.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>