split: deterministic-tests, obsidian-plugin, local-cli, test-client, frontend root
New deterministic-tests workspace: scripted multi-client harness against
a real server (~110 scenario tests, server-control, managed-websocket,
test-runner). Updates to existing workspaces: obsidian-plugin (settings,
cursors, plugin entrypoint), local-client-cli (args, cli, file-watcher,
node-filesystem, path-utils + tests), test-client (mock-agent/client,
cli, error tracker). Bumps frontend root package.json/lock and adds
eslint config tweaks.