feat(blocks): add typed personalization resolution

packages/blocks/src/document.ts

@@ -1,5 +1,6 @@
 import type { BlockRegistry, ReadonlyBlockRegistry } from "./registry.ts";
 import type { DocumentKindDefinition } from "./kinds.ts";
+import { resolveDocumentVariables } from "./variables.ts";
 import {
   DEFAULT_LIMITS,
   type BlockDocument,
@@ -68,6 +69,8 @@ export function validateDocument(
     });
   const meta = kind.metadata.parse(document.meta, "meta");
   if (!meta.ok) errors.push(...meta.errors);
+  const variables = resolveDocumentVariables(document, kind.variables);
+  if (!variables.ok) errors.push(...variables.errors);
   const ids = new Set<string>();
   let count = 0;
   walkBlocks(document.root, (node, depth) => {