docs: revise the M4 slice to a React console, and say what it defers

The first version specified server-rendered HTML with no build step. Superseded: the console is
Vite, React 19, Tailwind and a component catalog, because the platform this becomes is not a
debugging page. Functionality first and polish second -- the stack is scaffolded now so nothing
is rebuilt later, and framer-motion, react-three-fiber and premium components are installed by
task 1 and used by nobody until the deferred slice, which names why each one is wrong to reach
for today.

The architectural spine is stated before any task, because a task that gets it wrong produces
working code pointed the wrong way. sync/mcp/tools.py already froze four tools with response
rules written for an agent -- never return file contents, stay shallow, paginate, carry
provenance -- and those are the right rules for a human console for the same reasons. So the
HTTP layer is a transport over GraphSurface rather than a second API: one contract, two
consumers, and most of it already built and tested. features/ is named after graph entities, so
a directory that is not an entity is a smell.

Task M4-A is unaffected and continues: view models over the graph are technology-agnostic, and
a React console needs exactly that data layer.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: stroland02