Complete the 2.6.0 workspace milestone by adding explicit host-out export and immutable-baseline diff across the CLI, Python SDK, and MCP server.
Capture a baseline archive at workspace creation, export live /workspace paths through the guest agent, and compute structured whole-workspace diffs on the host without affecting command logs or shell state. The docs, roadmap, bundled guest agent, and workspace example now reflect the new create -> sync -> diff -> export workflow.
Validation: uv lock, UV_CACHE_DIR=.uv-cache make check, UV_CACHE_DIR=.uv-cache make dist-check, and a real guest-backed Firecracker smoke covering workspace create, sync push, diff, export, and delete.
Break the updated workspace vision into a checked-in roadmap from 2.4.0 through 3.1.0 so later implementation can be driven milestone by milestone.
Link the roadmap from the vision doc and keep each release slice scoped to one product capability, from the workspace contract pivot through shells, export/diff, services, snapshots, secrets, networking, and GA promotion.
This is a docs-only planning scaffold; runtime behavior stays unchanged in this commit.
