fix: reset animation fps limit to native when custom field is cleared on blur

[klfk]

Description

Fixes #8119

Problem

When a user set a custom animation fps limit (e.g. 60), then cleared the input field and clicked away, nothing happened — the native button stayed inactive, the field stayed empty, and the previous custom value was still in effect (no visual feedback).

Root cause: The onBlur validator called form.handleSubmit() with an empty string, which failed the onChange validator ("Must be a number"), so onSubmit was never called. The resetToDefaultIfEmptyOnBlur prop had no effect because the form's defaultValues.fpsLimit was "" — already empty.

Fix

In the onBlur validator, explicitly detect an empty value and call setfpsLimit(1000) to reset to native, making the native button active and clearing the indicator — which matches the expected behavior described in the issue.

// Before
onBlur: () => {
  void form.handleSubmit();
},

// After
onBlur: ({ value }) => {
  if (String(value) === "") {
    setfpsLimit(1000);
    form.setFieldValue("fpsLimit", "");
    savedIndicator.hide();
    return;
  }
  void form.handleSubmit();
},

Also removed the now-redundant resetToDefaultIfEmptyOnBlur prop from <InputField> since blur is handled manually.

Testing

1. Go to Settings → search animation fps limit
2. Enter 60 in the custom limit field → click away → ✅ saved indicator flashes, native button inactive
3. Clear the field → click away → ✅ native button becomes active, field stays empty

[github-actions]

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[fehmer]

If the stored value was 60 shouldn't it reset to 60 on empty input.
In addition the field should not be marked with an error if the user clicks on native:

[fehmer]

duplicate #8130