[core, form] Add merger option

Author: x0k

.changeset/eleven-squids-protect.md

@@ -0,0 +1,5 @@
+---
+"@sjsf/form": minor
+---
+
+Add `merger` form option

mkfile

@@ -23,6 +23,8 @@ f/:
     pnpm run build
   c:
     pnpm run check
+  t:
+    pnpm run test
   popd
 
 ds/:

packages/form/src/core/default-merger.ts

@@ -0,0 +1,12 @@
+import mergeAllOf, { type Options } from "json-schema-merge-allof";
+
+import type { Merger } from "./merger.js";
+import type { Schema } from "./schema.js";
+
+export const defaultMerger: Merger = {
+  mergeAllOf(schema) {
+    return mergeAllOf(schema, {
+      deep: false,
+    } as Options) as Schema;
+  },
+};