build: ship prebuilt dist/ for install-from-git robustness

npm does not make esbuild resolvable to the root prepare script when preparing
a git dependency for a global install, so the prepare-time build cannot run in
that environment. Commit the prebuilt workspace-server bundle (minified, no
sourcemaps) so 'npm install -g git+...#<sha>' has a runnable artifact and
prepare-build.js takes its prebuilt-dist branch instead of trying to build.

This is the pinned-branch deploy artifact; local development still rebuilds
dist/ via npm run build.

Author: Federico Liva