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>

vitest.config.ts

@@ -0,0 +1,34 @@
+import { fileURLToPath } from "node:url";
+
+import { defineConfig } from "vitest/config";
+import react from "@vitejs/plugin-react";
+
+// The binder splits into a pure headless core (bindings, active-state reducer,
+// rect-registry) that is node-safe, and a React surface (provider, form
+// renderer, overlay, registry hooks) exercised in a DOM. Tests whose filename
+// ends in `.dom.test.{ts,tsx}` run under happy-dom; everything else runs in
+// Node, which is faster. The react plugin lets the `.tsx` sources compile.
+//
+// The one runtime dependency, `@citation-evidence/engine`, resolves through its
+// package `exports` map (`.` and `./shared`) via the sibling-checkout link. The
+// engine ships raw TypeScript that uses its own `@shared/*` / `@engine/*` path
+// aliases internally; tsc honours those via tsconfig `paths`, but Vite does
+// not read tsconfig, so we mirror them here as resolve aliases. Nothing in this
+// package imports `citation-evidence` internals — the aliases only exist so the
+// linked engine source resolves.
+const enginePath = (rel: string) =>
+  fileURLToPath(new URL(`../citation-engine/src/${rel}`, import.meta.url));
+
+export default defineConfig({
+  plugins: [react()],
+  resolve: {
+    alias: [
+      { find: /^@shared\//, replacement: `${enginePath("shared")}/` },
+      { find: /^@engine\//, replacement: `${enginePath("engine")}/` },
+    ],
+  },
+  test: {
+    environmentMatchGlobs: [["**/*.dom.test.{ts,tsx}", "happy-dom"]],
+    globals: false,
+  },
+});