Point README at citation-evidence umbrella during MVP phase

Code lives upstream in citation-evidence/src/work/ during the MVP.
README documents that, points at SharedContracts.md, and reiterates
the no-import-from-binder rule from the dependency map.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

README.md

@@ -1 +1,17 @@
-A document review workspace.
+# citation-work
+
+A document review workspace — the React surfaces for the review workflow:
+collection list, viewer shell, evidence sidebar, annotation create flow,
+form-binding side-by-side layout.
+
+## MVP status: INTENT only
+
+During the citation-evidence MVP, code lives upstream in
+[`citation-evidence`](../citation-evidence/) under `src/work/`. This repo
+currently holds `INTENT.md` describing what will move here. Contract
+changes belong in
+[`citation-evidence/wiki/SharedContracts.md`](../citation-evidence/wiki/SharedContracts.md),
+not here.
+
+Per the dependency map, work depends on `shared/`, `engine/`, `anchor/`,
+and `source/` — and **may not** import from `binder/`.