fix(web): disable the enlarge button along with its field

Copilot review round 2 on #2109. A disabled form (a tool call in flight) left
the enlarge button live, and activating it swapped in a text area that mounts
disabled — so the focus hand-off targeted an unfocusable element and keyboard
focus was dropped to the document.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JTHVxSu8AUgHRLvo1ntZ8H
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/components/groups/SchemaForm/SchemaForm.test.tsx

@@ -1954,4 +1954,19 @@ describe("SchemaForm multiline strings (#2042)", () => {
     await user.keyboard("{Enter}more");
     expect(textarea.value).toBe("typed\nmore");
   });
+
+  // A disabled form (a tool call in flight) must be inert as a whole: a live
+  // button there would swap in a text area that mounts disabled, cannot take
+  // focus, and so drops keyboard focus to the document.
+  it("disables the enlarge button along with the field", () => {
+    renderWithMantine(
+      <SchemaForm
+        schema={stringSchema}
+        values={{}}
+        onChange={vi.fn()}
+        disabled
+      />,
+    );
+    expect(screen.getByRole("button", { name: "Enlarge Note" })).toBeDisabled();
+  });
 });

clients/web/src/components/groups/SchemaForm/SchemaForm.tsx

@@ -713,6 +713,7 @@ export function SchemaForm({
             <FieldActions>
               <EnlargeButton
                 ariaLabel={`Enlarge ${label}`}
+                disabled={disabled}
                 onClick={() =>
                   setEnlargedFields(
                     (previous) => new Set([...previous, fieldName]),