feat(authz): generate Permission and Role union types

Emits sorted TS unions from the merged catalog so a typo in
can(ctx, "post:wrtie") is a compile-time error. Uses JSON.stringify
for string-literal escaping (not manual backslash/quote replace) so
role names containing raw newlines still produce valid TypeScript;
role names are not regex-validated like permission ids, so this
matters for the raw mergeCatalogs path.

packages/authz/src/codegen.ts

@@ -0,0 +1,26 @@
+import type { AuthzCatalog } from "./types.ts";
+
+function union(values: string[]): string {
+  if (!values.length) return "never";
+  // JSON.stringify escapes backslashes, quotes, and control characters
+  // (including raw newlines, which the registry does not reject in role
+  // names and which would otherwise break out of the string literal).
+  return values
+    .slice()
+    .sort()
+    .map((value) => JSON.stringify(value))
+    .join(" | ");
+}
+
+/**
+ * Emit compile-time unions for the registered permissions and roles, so a
+ * typo in can(ctx, "post:wrtie") is a type error rather than a silent false.
+ */
+export function generatePermissionTypes(catalog: AuthzCatalog): string {
+  return `// Generated by \`wrnexus authz generate\`. DO NOT EDIT.
+
+export type Permission = ${union([...catalog.permissions.keys()])};
+
+export type Role = ${union([...catalog.roles.keys()])};
+`;
+}