fix: use relative path for server module in Docker

The Docker container doesn't have @peerverity/ai-delegate in
node_modules since it's the package being built, not a dependency.
Changed to use relative path ./dist/server/index.js instead.

🤖 Generated with [Claude Code](https://claude.com/claude-code

)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>