refactor: move the JSON-object draft parser into utils

`react-refresh/only-export-components` rejects a non-component export from a
component module, so `parseObjectDraft` could not live beside
`JsonObjectInput`. It is a pure transform, which puts it in `utils` under the
`lib`/`utils` rule anyway.

Also render the metadata hint's inline literals through `<Code>` rather than
markdown backticks, which a Mantine `Text` shows verbatim.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0177mPHAdECD18nLLCTwR5rh
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/utils/jsonObjectDraft.ts

@@ -0,0 +1,47 @@
+import type { JsonObject } from "@inspector/core/json/jsonUtils.js";
+
+/**
+ * What a JSON-object editor's draft text currently means: the object to emit,
+ * or why it cannot be emitted.
+ */
+export type JsonObjectDraft =
+  | { ok: true; value: JsonObject }
+  | { ok: false; error: string };
+
+/** A plain JSON object, i.e. not an array and not a scalar. */
+export function isJsonObject(value: unknown): value is JsonObject {
+  return value !== null && typeof value === "object" && !Array.isArray(value);
+}
+
+/**
+ * Read a JSON-object editor's draft text.
+ *
+ * Empty text is the object `{}` rather than an error — clearing the box is how
+ * "send nothing" is spelled, and an empty editor wearing a red error would read
+ * as broken.
+ *
+ * The two failure modes are reported separately because they are different
+ * mistakes: text that is not JSON at all is usually mid-edit, while text that
+ * is valid JSON but not an object (`[1,2]`, `"a"`, `42`) is a shape the caller
+ * cannot use no matter how finished it is.
+ *
+ * Lives in `utils` rather than beside its component because it is a pure
+ * transform — and because exporting it from the component's module trips
+ * `react-refresh/only-export-components`.
+ */
+export function parseJsonObjectDraft(text: string): JsonObjectDraft {
+  if (text.trim() === "") return { ok: true, value: {} };
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(text);
+  } catch {
+    return { ok: false, error: "Not valid JSON — changes are not applied" };
+  }
+  if (!isJsonObject(parsed)) {
+    return {
+      ok: false,
+      error: "Must be a JSON object (`{ … }`) — changes are not applied",
+    };
+  }
+  return { ok: true, value: parsed };
+}