Extract binder package from citation-evidence (EBIND-WP-0001)

Extracts citation-evidence/src/binder/ into this repo as the standalone
@citation-evidence/evidence-binder package: headless binding service +
in-memory link repo, active-state machine, the SharedContracts §7
rect-registry contract (registry, change pumps, hooks, SVG overlay), and
the target-neutral reference FormRenderer.

- toolchain mirrors sibling extracted repos (pnpm/tsc/vitest/eslint);
  imports rewritten from @shared/@engine aliases to the engine's
  @citation-evidence/engine package specifiers
- dependency boundary (engine + anchor only; no source/work/umbrella)
  enforced via eslint no-restricted-imports
- docs: extraction inventory + contract deltas, ADR-0001 (reference UI
  kept as supported exports), refreshed README/SCOPE/INTENT, populated
  capabilities index
- typecheck + lint green, 37 tests passing

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -1,19 +1,49 @@
 # 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.
+`@citation-evidence/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.
 
-## MVP status: INTENT only
+This is the canonical home of the binder implementation, extracted from
+`citation-evidence/src/binder/` (EBIND-WP-0001).
 
-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.
+## What this package owns
 
-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).
+- **Evidence links** — `EvidenceLink` repository + binding service
+  (`services/bindings.ts`, `repos/in-memory-links.ts`). Two query directions:
+  *all evidence for a target* and *all targets for an evidence item*. Emits the
+  canonical engine bus events (`EvidenceLinkCreated/Updated/Removed`,
+  `EvidenceItemActivated`).
+- **Active state** — the `(activeTarget, activeEvidenceItemId, activeAnnotationId)`
+  machine and React provider (`state/active.ts`) that the form UI, evidence
+  sidebar, and viewer adapter coordinate through.
+- **Rect registry contract** (SharedContracts §7) — a single registry into which
+  independent renderers publish `field` / `evidence-card` / `highlight` rects,
+  plus the change pumps, React hooks, and the SVG `Overlay` that draws the guide
+  (`visual-guide/`).
+- **Reference form UI** — `FormRenderer` and `FieldDefinitionForm`, kept as
+  supported, target-neutral exports (see `docs/adr/ADR-0001-reference-ui-surface.md`).
+
+`BinderProvider` composes all four concerns behind one mount.
+
+## Dependency boundary
+
+Per `citation-evidence/wiki/DependencyMap.md` §2, this package **may** depend on
+`citation-engine` and `evidence-anchor`, and **must not** depend on
+`evidence-source`, `citation-work`, or the umbrella `citation-evidence`. The MVP
+slice imports only `citation-engine` (shared types + event bus). The boundary is
+enforced by `eslint.config.js`. Shared-contract authority stays in the umbrella
+wiki.
+
+## Develop
+
+```bash
+pnpm install        # links @citation-evidence/engine from ../citation-engine
+pnpm test           # vitest (node + happy-dom suites)
+pnpm typecheck      # tsc -b --noEmit
+pnpm lint           # eslint (enforces the dependency boundary)
+```
+
+Requires a sibling checkout of `citation-engine` (see `.nvmrc` for the Node
+version). See `docs/extraction-inventory.md` for the extraction boundary and
+resolved contract deltas.