Federation and Bundler Decision — Bun + Rsbuild + Module Federation, Workspace State, Optional Chat

The single architectural decision the augment-it rewrite has been gated on. We federate. The bundler is rsbuild (not Vite). The workspace orchestrator is bun (not turbo). State of truth lives in @augment-it/workspace — a per-app package following the shared workspace conventions — not inside the chat package. The @lossless/in-app-agent chat surface is mounted as one consumer of that workspace through a typed WorkspaceAdapter; non-chat consumers (Window microfrontends, headless workflow scripts) consume the workspace directly. Tanuj's federation experiment proved Module Federation works but exposed a smoking gun around shared state; the singleton-module idiom on @augment-it/workspace dissolves that gun, because every consumer reads from the same instance.