Point README at citation-evidence umbrella during MVP phase

Code lives upstream in citation-evidence/src/anchor/ during the MVP.
README documents that, points at SharedContracts.md for the viewer
adapter contract, and notes anchor's dependency-map constraints
(imports shared/engine only).

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

README.md

@@ -1 +1,16 @@
-Evidence anchoring, selector, resolution for citations.
+# evidence-anchor
+
+Selector creation, resolution, and the `DocumentViewerAdapter` contract that
+every document viewer in the workspace implements.
+
+## MVP status: INTENT only
+
+During the citation-evidence MVP, code lives upstream in
+[`citation-evidence`](../citation-evidence/) under `src/anchor/`. 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, anchor depends on `shared/` and `engine/` only;
+nothing in `binder/`, `source/`, or `work/` may flow back into it.