Point README at citation-evidence umbrella during MVP phase

Code lives upstream in citation-evidence/src/binder/ during the MVP.
README documents that, flags the rect-registry contract as a
SharedContracts.md responsibility, and notes work/ may not import
binder.

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

README.md

@@ -1 +1,19 @@
-Connect evidence items to structured targets such as form fields, claims, requirements.
+# evidence-binder
+
+Connect evidence items to structured targets — form fields, claims,
+requirements — and render the visual guide that ties a target, its evidence
+card, and the source highlight together in the workspace UI.
+
+## MVP status: INTENT only
+
+During the citation-evidence MVP, code lives upstream in
+[`citation-evidence`](../citation-evidence/) under `src/binder/`. This repo
+currently holds `INTENT.md` describing what will move here. Contract
+changes — including the rect-registry contract that the visual guide
+depends on — belong in
+[`citation-evidence/wiki/SharedContracts.md`](../citation-evidence/wiki/SharedContracts.md),
+not here.
+
+Per the dependency map, binder depends on `shared/`, `engine/`, and
+`anchor/`. It must not be imported by `work/` (the UI talks to binder via
+the active-state context, not by direct import).