Add dataset library, extract-to-dataset, and render-time reference resolution

src/app/modals/UrlStateSync.ts

@@ -0,0 +1,26 @@
+/**
+ * Modal ↔ URL hash sync (docs/architecture/03 → "URL & Keyboard Integration").
+ *
+ * The coordinator calls these so a navigable modal (Datasets, Settings, Chart
+ * Builder) becomes a shareable / back-navigable location, e.g.
+ * `#datasets/dataset-<id>`. Full hash routing — view-state restore on load,
+ * Back/Forward — is milestone M6 (spec §01E, docs/architecture/04). Until then
+ * these are intentional no-ops so the coordinator's shape is final and M6 fills
+ * the bodies in without the call sites changing.
+ */
+
+import type { ModalName } from './types';
+import { getModalConfig } from './modal-registry';
+
+/** Reflect an open navigable modal (and optional sub-target) in the URL hash. */
+export function syncModalToUrl(name: ModalName, _arg?: string): void {
+  if (!getModalConfig(name)?.isUrlNavigable) return;
+  // TODO (M6, spec §01E): write `#${name}` / `#${name}/dataset-${arg}` to the
+  // hash via the routing layer (docs/architecture/04).
+}
+
+/** Return the hash to the underlying workspace when a navigable modal closes. */
+export function clearModalFromUrl(name: ModalName): void {
+  if (!getModalConfig(name)?.isUrlNavigable) return;
+  // TODO (M6, spec §01E): restore the pre-modal workspace hash.
+}