feat: establish TypeScript-aware frontend tooling

tests/fixtures/registry/forbidden/invalid-registry.ts

@@ -0,0 +1,13 @@
+type InvalidRow = Readonly<{
+  id: string;
+  target?: string;
+}>;
+
+export const INVALID_REGISTRY: Record<string, InvalidRow> = {
+  FIRST: { id: "duplicate", target: "missing" },
+  SECOND: { id: "duplicate" },
+};
+
+export const TARGET_REGISTRY = {
+  KNOWN: { id: "known" },
+} as const;